November 9, 2026 - Open Annihilation 0.9 Trailer: Return of the Boneyards

Fact sheet

Project

Open Annihilation

Tagline

Open Source, cross-platform re-implementation of Total Annihilation game engine.

Developers

Steve Gray, with contributors Silencer, Zane van Iperen and JulienS

Release

Version 0.9.0, 6 November 2026. First public release, version 0.2, on 27 September 2026, 29 years to the day after Total Annihilation's North American launch

Platforms

macOS 11 or later (Intel and Apple silicon, signed and notarized); Windows 64-bit, 32-bit including XP, Windows 11 on ARM and Windows 95, each with an installer; Linux x86-64 and ARM, including the Raspberry Pi; the Steam Deck, experimentally, with a package of its own; iPhone and iPad, built from source with Xcode

Languages

English, German, French, Spanish and Italian built in; Simplified Chinese (横扫千军), Japanese, Korean, Russian and Ukrainian from the Library, switching without a restart

Library

Over 3,000 community maps, 32 mods including TA Escalation, Rainbow Edition and Great War At Sea, 115 mutators, the Classic brain, five new races, the Cavedog map packs and bonus units, and language packs, from signed catalogues built into the game

Codebase

More than 1.7 million lines of C++20 on SDL3

Price

Free and open source. Requires a copy of Total Annihilation, sold on Steam and GOG, currently $1.49 on GOG. The original free demo, preserved on the Internet Archive, also works.

Licence

GNU General Public License version 3. The engine is free software and will stay that way.

Source code

github.com/open-annihilation/open-annihilation

Modding tools

Kbot, an MIT-licensed toolchain for Total Annihilation and TA: Kingdoms

Website

play.coreprime.net

Community

Discord

Online service

Core Prime, the rebuilt Boneyards service. Since 0.9 the Boneyards lobby is in the game, with a Core Prime account: the Galactic War, ladders for ranked play, QuickPlay on Core Prime's match queue, news, chat and paging, with battles played through Core Prime's relays. Its content catalogue is built into the Library. The full Matchmaking screen follows in a later release, and further releases in the 0.9 series are intended to bring mods and mutators into the galactic war. Register at coreprime.net

Press contact

Steve Gray, steve@coreprime.net

Author

Steve Gray on LinkedIn

Description

Short

Open Annihilation is a free, open source engine that plays the original 1997 real-time strategy classic Total Annihilation on modern macOS, Windows and Linux machines, on iPhone and iPad, and experimentally on the Steam Deck. It reads the game's own data files and save games from a copy bought on Steam or GOG, or from the original free demo, and aims to match the final official release, version 3.1c, in behaviour rather than reimagine it. Version 0.8, Rise of the Mods, adds a Library that installs over 3,000 community maps, 32 mods including TA Escalation, Rainbow Edition and Great War At Sea, five new playable races and language packs from signed online catalogues, in one place and without a restart. Version 0.8.5 added 115 mutators, small packages that change one game over the base game or any mod, version 0.8.6 added brains, computer players written in Lua and chosen for each computer seat, and a 3D camera with Full hardware acceleration, version 0.8.7 added a key editor that gives any action any key or mouse button, with layouts that can be shared, a new look for Settings and the Library, and an updater that installs a new release only when you say so and can roll back, version 0.8.8 drew big battles about 10x faster than 0.8.7 in the turned 3D view, version 0.8.9 paused a single-player game while the window is away and updated a Mac copy installed from the package in place, version 0.8.10 drew big battles about 5x faster than 0.8.9 in the turned 3D view, version 0.8.11 brought back the speed keys on AZERTY, QWERTZ and other keyboards, version 0.8.12 brought back the game's own update on macOS and added an update channel for Testing releases and settings to invert the 3D camera and the mouse zoom, version 0.8.13 runs the game on the faster graphics card of Windows laptops that have two, and version 0.9 brings back the Boneyards, the game's original online lobby, inside the game, with a Core Prime account and battles played through Core Prime's relays.

Long

Total Annihilation, designed by Chris Taylor and released by Cavedog Entertainment on 27 September 1997, is one of the most influential real-time strategy games ever made: three-dimensional units and terrain, physics-simulated projectiles, a streaming economy and a scale of warfare that later games spent years catching up with. The game is still sold today, but it was written for Windows 95 and 1997 hardware, and playing it on a current machine, especially a Mac or a Linux desktop, means compatibility layers, resolution hacks and luck. Open Annihilation's first release arrived on 27 September 2026, 29 years to the day later, and thirty-five releases have followed in under six weeks.

Open Annihilation replaces the original executable with a new, portable engine written from scratch. It ships no game content. Instead it loads the archives, maps, unit models, unit scripts, sounds and music from an installed copy of the retail game, including both expansion packs, The Core Contingency and Battle Tactics. The single-player campaigns, skirmish against the original computer players or against brains written in Lua, network games over the original protocol, mods, recorded games and the original save-game format all run in the new engine, and a built-in Library adds the community's maps, mods, mutators, races and languages from signed catalogues. Matches render at any resolution up to 8K with the original 8-bit look intact, drawn by the graphics card where there is one and by the processor where there is not, down to a 256 MB Windows XP machine or a Raspberry Pi. With Full hardware acceleration the camera can also leave the classic top-down view and turn the battlefield in 3D. Every action can take a key of the player's choosing, and on macOS, Windows and Linux the game looks for new releases itself and keeps the version before, so an update can be rolled back. A single-player or skirmish game pauses while the window is away, or keeps playing in the background if the player chooses.

Core Prime, the rebuilt Boneyards service, is in the game. Since 0.9 the Boneyards, Total Annihilation's original online lobby, opens from the main menu with a Core Prime account: the galactic war map with its planets and sectors, Recon, Chat, battle rooms, News, Ladders, profiles and Help, in Cavedog's own lobby screens, art and sounds, installed from Core Prime on the first entry. Ladders rank play on Two Player, Three Player and Galactic War ladders, players page each other and the Locator finds them, and QuickPlay finds a forming battle or hosts one through Core Prime's match queue, which pairs players by side, planet and skill bracket; the full Matchmaking screen follows in a later release. Battles are played through Core Prime's relays, so nobody needs to forward a port and players in different regions can play together. Further releases in the 0.9 series are intended to bring mods and mutators into the galactic war. Core Prime's catalogue of mods, map packs, bonus units and languages is built into the Library, and players register at coreprime.net. The engine also speaks the original game's network protocol, so cross-play with unmodified Total Annihilation clients is possible.

What it does today

• Plays the real game. Loads the retail game's archives, maps, units, scripts, sound, speech, music and movies, including both expansions. No content is bundled or redistributed, and saved games stay compatible with the original.
• Single player and multiplayer. The Arm and Core campaigns, skirmish against the original computer players, and network games hosted or joined over TCP/IP using the original game's protocol. GET MAP checks that your game can play the host's map before it downloads it, and says what is missing. The host can start a multiplayer game against computer players with no other human, unless the launch locks the options.
• The Boneyards. Total Annihilation's original online lobby is built into the game: ENTER on the Boneyards strip at the bottom of the main menu, or the B key, logs in with a Core Prime account, and REGISTER opens coreprime.net/register. It runs in Cavedog's own lobby screens, art and sounds, installed from Core Prime on the first entry, and Help and your Profile are there as they were.
  • The Galactic War: the war map of planets and sectors where Arm and Core fight for control, with Recon on any sector, and ranks earned from each side's war record.
  • Ladders for ranked play: Two Player, Three Player and Galactic War ladders, with published standings.
  • Matchmaking: Core Prime's match queue pairs players by side, planet and skill bracket. QuickPlay uses it to find a forming battle or host one, and the full Matchmaking screen follows in a later release.
  • News: Core Prime's news posts, ticker and announcements, in the lobby.
  • Chat and paging: chat rooms and battle rooms, pages to any player who is online, and the Locator to find one.
  • Relayed battles: battles are played through Core Prime's relays, so nobody needs to forward a port and players in different regions can play together. They play 3.1c, Core Contingency or Battle Tactics, without mods or mutators: the Boneyards switches a mod off for you, after asking, and offers to switch it back on when you leave. Further releases in the 0.9 series are intended to bring mods and mutators into the galactic war.
• The Library. Mods, map packs, languages and expansions from signed online catalogues, installed, updated, held, rolled back and removed in one place. Core Prime's catalogue is built in: over 3,000 community maps, 32 mods including TA Escalation, Rainbow Edition and Great War At Sea, 115 mutators, the Classic brain, five new races, the Cavedog map packs and bonus units.
• Mods. A mod describes how it differs from 3.1c in one profile file, and the engine applies the standard hacks it names, with no code for any particular mod. Mods that add a third or fourth side put every race on the skirmish Side button, and a mod can have more than 256 weapon types and more than five sides. A mod with its own main menu shows a small Boneyards ENTER plate in its corner, which its manifest can move or hide.
• Mutators. A mutator is a small package that changes one game, over the base game or any mod: tougher Commanders, faster builders, more metal, units switched off and more. The Library's Mutators tab offers 115, translated from the mutators players made for Total Annihilation, and the MUTATORS button on the skirmish setup, the campaign launch and the battle room switches them on. Recordings and saved games keep their mutators.
• Brains. A brain is a computer player written in Lua, chosen for each computer seat in the skirmish setup, for a campaign's computer players and in the battle room; the built-in computer player stays the default. Classic, the built-in computer player written in Lua and playing exactly as it does, is the first in the Library's Brains tab, and its source is in open-annihilation/ai-brains. Each seat runs in its own sandbox, so brains play the same on every machine, network games stay in step and recordings replay.
• A 3D view. With Full hardware acceleration, Alt+drag on the battlefield (Option+drag on a Mac) turns the camera and Alt+R puts the classic top-down view back. The 3D view is drawn through Metal on a Mac and through Vulkan on Windows 7 to 11 and Linux. Full also draws water ripples, coastal waves, underwater shimmer and naval reflections, and turns on coloured weapon lighting, nanolathe glow, wreck glow and heat distortion by default; Off and Basic acceleration keep the game's own look. Turning the camera does not stutter: the ground is kept while the view moves, and ground coming into view is drawn one detail level softer until the camera stops. Big battles in the turned view draw about 5x faster than they did in 0.8.9: the graphics card draws the units, casts their shadows, adds the lights and heat and sends the picture straight to the window, so the picture reaches the screen sooner, and edge smoothing uses the graphics card's 4x multisampling, which smooths wide windows such as 2560x1440 too. Settings › Controls can invert the 3D camera pan, the 3D camera rotation and the mouse zoom.
• Any key for anything. Every action in the game, in Open Annihilation's own screens and in the menus can take a key of your choosing, or a mouse button, in a key editor that finds an action by the key you press and warns when two actions want the same key. Layouts can be cloned, described and shared as .oakeys files or as text, the Library's Keys tab holds them, 3.1c's own keys work as they did, and keys set with older key-remapping patches and tools carry into a layout of your own. Pads and touch keep working when keys move. The speed keys are on the keys that type + and - on AZERTY, QWERTZ and other keyboards, as in 3.1c, and the key editor names them as your keyboard labels them.
• Double-click selects. Settings › Controls › Double-click selects chooses what a double-click on a unit selects: that type on screen, the default, as the community patch does, or every unit of that type on the map, as 3.1c does. Ctrl+Z still selects that type on the whole map.
• Pauses when you look away. Settings › Controls › When the window loses focus chooses what a single-player or skirmish game does while you are away: it pauses and resumes by itself when you come back, the default, or keeps playing in the background. A pause you chose stays until you resume it, and multiplayer games are never paused.
• Updates itself. On macOS, Windows, including XP, and Linux, Open Annihilation looks for a newer release every time it starts and every hour while it runs, installs one only when you say so, and keeps the version you had, with its settings, so Roll back in Settings › Updates puts it back. On a Mac, a copy installed from the package updates in place, and macOS asks for an administrator's password with its own prompt when only an administrator can replace the app; the game itself never runs with an administrator's rights. Mac players install 0.8.12 by hand, once, and from 0.8.12 on Macs update in the game again; players on 0.8.8 or older, on every system, also install by hand, and the game's update screen opens the release page for them. Settings › Developer › Update channel lets a copy take Testing releases before everyone else; Stable is the default.
• A new look for its own screens. Settings, the Library, the key editor, the update screens and the first-run setup are drawn in the Barlow typeface and sized for the window; a Classic look draws them in the game's own font, and the game's own screens are unchanged. The Mutators and Maps windows have the same look, and every question Open Annihilation asks shares the new footer and buttons.
• Recorded games. Plays recordings made by the original demo recorder and records its own network games in the same format.
• Ten languages. English, German, French, Spanish and Italian built in, and Simplified Chinese, Japanese, Korean, Russian and Ukrainian from the Library, with every word of the engine's own interface translated and Unicode chat between players.
• Modern hardware, original look. Full hardware acceleration, smooth motion at up to 120 frames a second between the game's 30 ticks, anti-aliasing, modern fonts, and zoom from the whole map down to the ground, with the 8-bit palette rendering intact. On Windows laptops with two graphics cards, NVIDIA Optimus or AMD switchable graphics, the game runs on the faster, separate card, and a choice made in Windows' Graphics settings or in NVIDIA's or AMD's control panel still wins.
• Old hardware too. Deterministic across x86 and ARM, 32-bit and 64-bit, and built to run on a 256 MB, single-core Windows XP machine or a Raspberry Pi.
• Native on every platform. Separate builds for macOS, Windows and Linux, a touch interface for iPhone and iPad, and experimental support for the Steam Deck with its own controls.
• Free software. Released under the GNU GPL version 3, with a test suite that checks the engine against the data of an installed copy of the game.

What's new since launch

Version 0.2 shipped on 27 September as a playable single-player engine for macOS, Windows and Linux. Thirty-five releases later, the 0.8 series, Rise of the Mods, has turned the engine into a platform for everything the community has made for the game, and 0.9 brings back the Boneyards, the game's original online lobby. The major additions, in the order they landed:

• Signed and notarized macOS app with an installer, and smooth motion at up to 120 frames a second, interpolating units, projectiles, effects and the camera between the game's 30 ticks. (0.5)
• Old and small computers. A 32-bit Windows build that runs on Windows XP with 256 MB of memory and a Pentium III, Linux builds back to glibc 2.28 and for the Raspberry Pi, and battles up to 45% faster on one core, drawn across spare cores on bigger machines. The engine plays its own movies and music, so FFmpeg is gone and packages shrank by a fifth. (0.6)
• The same game on every machine. Angles and lengths are computed with integer arithmetic, so x86 and ARM, 32-bit and 64-bit, play every game identically, and results no longer depend on what is drawn. Aircraft fight and missiles fly as in 3.1c. (0.6)
• Multiplayer. Host or join a game over TCP/IP from the Multiplayer menu and set it up in the battle room. The engine speaks the original game's protocol, so cross-play with native Total Annihilation clients is possible. (0.6.1)
• Full hardware acceleration. The graphics card draws the whole battlefield, with vertical sync and anti-aliasing up to 16x, and the processor still draws every frame where there is no card. (0.7)
• Mods. The OAMOD profile standard: a mod states how it differs from 3.1c in one file, choosing from 90 standard hacks in 16 areas, from computer players and aircraft to the interface and weapons, plus unit-script extensions. A Mods page switches between them without restarting, a Developer Mode tries any hack on any mod, and a mod packs into one .oamod file that installs with a double-click or a drop onto the window. (0.7, 0.7.1)
• iPhone and iPad. Touch controls made for the game: tap to move, a build drawer, an order wheel on a long press and pinch to zoom. The app copies the game data from your own copy on first start. It is built from source with Xcode; there is no App Store release. (0.7)
• Languages. English, French, Italian, German and Spanish from the translations in the game data, modern fonts with outline and shadow at 50% to 300%, and then the whole game in Simplified Chinese, 横扫千军, with a bundled font, system input methods for chat and save names, and Unicode chat that keeps non-Latin text intact between players. Languages come as packs, so more can be added. (0.7, 0.7.2)
• Your files in Documents. Saved games, screenshots, recordings and mods live in an Open Annihilation folder in Documents, a settings dialog reachable from the OA button covers everything with a documented page per setting, and downloaded saves, archives and recordings can no longer write outside their folders. (0.7, 0.7.1)
• Steam Deck, experimentally: the Linux build added to Steam as a non-Steam game, with the right trackpad as the pointer, grips, rings for orders and building, prompts and haptics. (0.7.1)
• Demo recorder. Recordings made by the original game's demo recorder play back from the command line, and the engine records its own network games in the same .tad format. (0.7.1)
• The view. Zoom out until the whole map fits, smooth zoom that stays on the point under the pointer, every resolution the display offers including 4K and ultrawide, and explosions that flash as in 3.1c, with a Full, Reduced or Off setting for players sensitive to flashing light. (0.7.2)
• A steadier view and more room. The ground no longer shimmers while the camera follows a unit at any zoom, the view can reach past the map's edge by a chosen amount, the side panel and bars can keep the original game's size, and the window's frame hides while you play. Computer players build from each builder's whole list as in 3.1c, and a game can be hosted or joined straight from the command line. (0.7.3)
• Closer to 3.1c, and on Windows 95. Mission briefings with a turning planet, a scrolling panorama and the wind and gravity, build mode that ends when Shift is let go, Full graphics that hold up in the biggest mod battles, a Steam Deck package of its own, and a game executable cut from 16.9 MB to 10.9 MB on macOS. The engine also builds from source for Windows 95, the system the original game was written for, a contribution from Zane van Iperen. (0.7.4)
• The Library. One place for everything you add to the game. Mods, map packs, languages and expansions come from signed online catalogues and are installed, updated, held, rolled back and removed from tabs for Active, Mods, Maps, Languages, Updates and Registries, with previews, filters, tags and search. Other registries can be added by address or by opening an .oareg file. (0.8)
• Over 3,000 community maps. The skirmish and battle room list every map, installed or not, in one list; a map not yet installed reads Available, and GET MAP fetches it from the battle room. Map packs come as .oamap files, and the 16 Cavedog map packs are in the catalogue. (0.8)
• The mods. Core Prime's catalogue is built in and already offers 14 mods: TA Escalation, Rainbow Edition, Talon, The Lost Legacy, Rhyoss, Mynn, The Final Frontier, World Domination, TA:UIP, TA:UCP, UTASP, TABA and UberHack among them, plus Cavedog's bonus units. (0.8)
• Five new races. Argon, Mynn, Rhyoss, Talon and The Lost Legacy join Arm and Core. Mods with a third or fourth side show every side on the skirmish Side button, and a side chosen under one mod opens on a race under another. (0.8)
• Three more languages, and the whole interface translated. German, French, Spanish and Italian are built in; Simplified Chinese, Ukrainian and Korean download from the Library and switch without a restart. Every word of the engine's own interface is translated, and text that does not fit a 3.1c button shrinks rather than being cut. (0.8)
• Windows 95 as a first-class build, with installers for all four Windows packages that set up the Start Menu, Add/Remove Programs and the file types. A first-run setup chooses your language and reads the GOG installers for Windows and macOS directly, copying the game once into Documents. Launch files (.oalaunch) let a launcher, a server or a shortcut start a fully set-up battle room. (0.8)
• Computer players that play a mod as its author meant. They follow a mod's whole AI profile and build lists as 3.1c does, so in TA Escalation they go on to tiers 3 and 4 instead of building factories without end, and a computer player's silo stockpiles its nukes. Saved games load in a fraction of the time, a first-run copy that stopped part way carries on, a Smooth motion setting can draw units 30 times a second as the original did, and the zoomed-out view draws faster. Argon, Total Mayhem and TA: Zero join the Library. (0.8.2)
• Race and multiplayer mods. A unit script with a deep expression runs as in 3.1c, so Devolution's Command Beacon teleports the Commander, a third side draws its own panel art, as Rumad does, and a frame draws about a millisecond faster zoomed far out. The Library grows to 22 mods with The Pack, XTA, Armored Typhoon, xubor mod and Great War At Sea, and its maps are tagged by the world their tiles come from and, for naval mods, by a sea start. (0.8.3)
• Every side's orders, and a queue you can rearrange. On the order page of a side other than Arm and Core, such as the Guardians of Kadesh in TA: Zero and TA: Excess or the Talon, FIRE ORDERS, CLOAK, ON/OFF and MOVE ORDERS now work as Arm's and Core's do, and a mod's own settings for one of Cavedog's downloadable maps play over the map pack's terrain. With Shift held, a queued building can be dragged onto another site, a sunken wreck is reclaimed on the sea bed where it is drawn, ground units find their paths as in 3.1c, and the Full tier loads on graphics cards whose Vulkan driver ran out of memory as a match loaded. (0.8.4)
• Mutators. A mutator is a small package that changes one game, over the base game or any mod: tougher Commanders, faster builders, more metal, units switched off and more. The Library has a new Mutators tab with 115 to start with, translated from the mutators players made for Total Annihilation, and a MUTATORS button on the skirmish setup, the campaign launch and the battle room switches them on. In a network game the host chooses, the other players see the set, and GET MUTATORS fetches any they are missing from Core Prime; recordings and saved games keep their mutators. A mutator is a manifest, a short Lua script and the files it needs, and Modding Info on mods.coreprime.net explains how to make one. (0.8.5)
• Closer to 3.1c in the hand. An order armed from its button ends when Shift is let go, placing a building keeps the arrow cursor so the site's outline sits under its point, build queue counts are written in the game's own font as 3.1c writes them, and damaged aircraft choose a repair pad as 3.1c does, so replays and games with 3.1c players no longer part ways when a pad is built or destroyed. A game that opens in full screen holds the pointer from the start, and a new Fog of War setting for the Full tier draws the fog's edges Smooth, as before, or Classic, hard and stepped with the game's own fog tiles as 3.1c does. (0.8.5)
• Brains: computer players written in Lua. A brain is a computer player written in Lua, chosen for each computer seat in the skirmish setup, for a campaign's computer players and in the battle room; the built-in computer player stays the default. The Library has a new Brains tab, and .oabrain files open in the game. Classic, the built-in computer player written in Lua and playing exactly as it does, is on Core Prime as the first brain, to play against and to learn from, and its source is in open-annihilation/ai-brains. Each seat runs in its own sandbox with a fixed allowance a tick, so brains play the same on every machine, network games stay in step and recordings replay, and a brain that stops hands its seat back to the built-in player on the next tick. Modding Info on mods.coreprime.net and the OABrain standard explain how to make one. (0.8.6)
• A 3D camera and new effects. With Full hardware acceleration, Alt+drag on the battlefield (Option+drag on a Mac) turns the camera, Alt+Shift+drag pans it and Alt+R puts the classic view back; a match always starts in the classic top-down view. The 3D view is drawn through Metal on a Mac and through Vulkan on Windows 7 to 11 and Linux where the graphics driver offers it, and Windows XP and 95 keep the classic view. Coloured weapon lighting, nanolathe glow, wreck glow and heat distortion are on by default with Full acceleration and off with Off or Basic, which keep the game's own look, and Full adds water ripples, coastal waves, underwater shimmer, naval reflections and aircraft shadows that grow softer and fainter with altitude. Director renders of recordings can be drawn by the graphics card, so videos show the effects and the water, with a director script's cameras turning in 3D. (0.8.6)
• Any key for anything. Every action in the game, in Open Annihilation's own screens and in the menus can take a key of your choosing, or a mouse button, in a new key editor (Settings › Controls › Key layout › Edit keys…) that shows each action with its keys, finds an action by the key you press, warns when two actions want the same key and clones a layout so you can rename and describe it. The Library has a new Keys tab for layouts, and Core Prime can carry them; Share My Custom Keys saves a layout as an .oakeys file or copies it as text for a forum or a chat, and Paste Someone's Layout shows each change a pasted layout makes before you apply it. A key can be bound by its letter, so it follows your keyboard's layout, or by its place, so it stays where it sits, and on a Mac the modifier keys read Cmd, Option, Ctrl and Shift. Keys set with older key-remapping patches and tools carry into a layout of your own, and 3.1c's keys work as they did: the camera bookmarks, every Ctrl+letter selection by the units' categories and the damage-bar keys, with any unit tag the game or a mod defines free to take a key of its own. A keys overlay (Cmd+/ on a Mac, Ctrl+/ elsewhere) shows the keys you have in a match, Show keys on buttons, off by default, puts each order button's and build cell's key in its corner, and Settings › Accessibility gathers Hold to confirm for self-destruct and surrender, Hold keys that latch and the Double press time. Pads and touch keep working when keys move. (0.8.7)
• A new look for Open Annihilation's own screens. Settings, the Library, the key editor, the update screens and the first-run setup are redrawn in the Barlow typeface, in title case, with one clear main button in each view; Settings › User Interface › Look chooses Modern, the default, or Classic, which draws them in the game's own font, and the game's own screens are unchanged. Interface size (Auto to 400%) and Window size (Auto, Compact, Regular or Large) set how large these screens draw, and dialogs opened during a match use the same type as from the menus. The Library is laid out as Settings is, with one list of sections down the left, the open section's filters and tags under it, a heading with the search box and the chosen entry's details in a card; it gathers maps by their world, ice, lava, desert and the others, under their own heading, and map pictures keep the map's shape, centred on black, where long or tall maps were stretched to a square. The in-game menu has an OA Settings button, and Move overlays in Settings › Accessibility lets you place the keys overlay, the latched keys and the chat line. The new screens and settings are in German, French, Spanish and Italian, and the Japanese, Korean, Russian, Ukrainian and Simplified Chinese packs are updated for 0.8.7, the key editor included. (0.8.7)
• Open Annihilation updates itself. On macOS, Windows, Windows XP and Linux it looks for a newer release from a signed feed every time it starts and every hour while it runs, and never installs one until you say so. It keeps the version you had, with its settings, so Roll back in Settings › Updates puts it back, and if a new version fails to start twice in a row the previous one comes back by itself. Check for updates, Download automatically and Install updates choose how much it does on its own. (0.8.7)
• More weapons, more sides, and allied sight. A mod can now have more than 256 weapon types, up to 65,536, and load more than five sides, up to 32; a mod that raises either plays only between Open Annihilation machines, and every engine limit now has its own page beside the standard hacks in the mod docs. In a mod that shares allied line of sight, the ground your allies have explored shows on the map and the minimap alike, grey where nobody sees it now. (0.8.7)
• Repairs, the minimap, the water and the 3D camera. A repair costs the unit doing the repairing, as in 3.1c: a repair pad pays for the aircraft on it and a builder for the unit it repairs, an ally's included, so the bottom bar shows the energy on the pad or the builder; saves made while a unit was being repaired, and recordings with a repair in them, from 0.8.6 or earlier, may not play on exactly as they did. The minimap shows what the map shows, as in 3.1c, the ground you have explored and your sight, where it had shown an ally's exploration and, with Permanent line of sight, the whole map while the battlefield stayed black. Underwater metal patches blend into the water and grey with the fog of war, lava worlds show no water effects, coastal waves take the colour of the shore under them, and the dithered fog of war stays fine at every zoom. A unit leaving a factory drives off over its platform at every camera position, and a ground unit standing on a building's platform or yard is drawn over it. The 3D camera no longer snaps back to the top-down view when it is turned low or zoomed out over a large map, the Arm Aircraft Plants' runways show in it, and a building's base lies on sloping ground instead of sinking into it. Windows 95 can save again, Windows XP needs less memory, aircraft past the map's edge can be selected, and Graphics › New unit shadows, on by default, can be turned off to draw every unit's shadow as the original game does. (0.8.7)
• Big battles in the 3D view, about 10x faster. With Full hardware acceleration, in a 550-unit battle on Lava Highground, measured on an Apple M5 at 1512x917, the camera turned low across the map runs about 10x faster than in 0.8.7, zoomed fully out about 16x faster, while turning about 9x faster, and an idle match about 4x faster. Turning the camera no longer stutters: the ground is kept while the view moves, and the graphics card is no longer sent the whole of its texture store again every few frames. While the camera moves, ground coming into view is drawn one detail level softer, and sharpens once the camera stops. (0.8.8)
• Double-click selects, and a building that stays on the map. Settings › Controls › Double-click selects is new: a double-click on a unit selects that type on screen, the default, as the community patch does, or every unit of that type on the map, as 3.1c does, and Ctrl+Z still selects that type on the whole map. A building can no longer be placed where it reaches past the edge of the map the view shows, such as a geothermal plant over a vent below the map's bottom edge: its outline turns red, and computer players, recordings and games with 3.1c machines are unchanged. The turned 3D camera's pointer stops at the map's edge, as the classic view's does. When closing the window, Alt+F4 or Cmd+Q asks whether to surrender, Enter leaves the game and Escape still answers No; the question the in-game menu's Exit asks is unchanged. (0.8.8)
• GET MAP checks your game first. GET MAP checks whether your game can play the host's map before it downloads it, and says what is missing, for example "Needs Core Contingency, which is off. Turn it on in the Library." When the installer refuses a map, the battle room now says why. (0.8.8)
• Mutators and Maps in the new look, and fixes. The Mutators and Maps windows have the look of Settings and the Library: the OPEN ANNIHILATION title, and Settings' buttons, filters, drop-downs and search boxes. The Library's list of sections scrolls past the entry you chose, where it snapped back to it. Choosing what happens when a new key is already in use no longer stalls the game: the question opens in a fraction of the time, and moving the pointer over it no longer hangs. On Windows, a folder or file name with characters outside the system's code page, such as a user name in Cyrillic or Chinese, no longer stops the game with "filesystem error: in __wide_to_char: Illegal byte sequence", and map packs in such a folder can be played again. The new settings and messages are in German, French, Spanish and Italian. (0.8.8)
• The game pauses when you look away. Settings › Controls › When the window loses focus is new: a single-player or skirmish game pauses while you are away and resumes by itself when you come back, the default, or keeps playing in the background. A pause you chose stays until you resume it, and multiplayer games are never paused. (0.8.9)
• Macs update in place. A copy installed from the package updates in place. When only an administrator can replace the app, macOS asks for an administrator's password with its own prompt; cancelling leaves the version you have, and the game offers to try again. The game itself never runs with an administrator's rights, and an update that could not be installed no longer leaves the game on the setup screen: the version you had starts again as the Finder starts it. Mac players on 0.8.7 or 0.8.8 install 0.8.9 by hand, once, from the .pkg; from 0.8.9 on, the game updates itself on macOS too. Updates install from the release's own packages on every platform. (0.8.9)
• The update screens in the new look, and a clear message about Documents. The update screens have the look of Settings and the Library: the OPEN ANNIHILATION title, Settings' buttons, and a footer that no longer runs past the window's edge, and every question Open Annihilation asks shares the new footer and buttons. When macOS refuses Open Annihilation access to your Documents folder, the game says so and how to allow it, where it started the first-run setup again. The new settings and messages are in German, French, Spanish and Italian. (0.8.9)
• Big battles in the 3D view, about 5x faster. With Full hardware acceleration, in a 550-unit battle on Lava Highground, measured on an Apple M5 at 1512x917, big battles draw about 5x faster than in 0.8.9 in the turned 3D view: the camera low across the battle about 5x faster, close up about 5.5x, while turning about 5x and zoomed fully out about 3x. Turning and panning stay smooth: the ground coming into view is prepared a little each frame before it is needed, so a moving camera no longer stalls when the view passes the edge of the ground it holds. The graphics card does more of the work: it draws the units from their models, casts their shadows, adds the lights and heat, and sends the picture straight to the window, and the picture reaches the screen sooner after you press a key or move the mouse, because the game no longer waits for the graphics card to hand each frame back. Lights and shadows may differ from 0.8.9 by a pixel at their edges. Edge smoothing uses the graphics card's 4x multisampling, as smooth as before, and wide windows such as 2560x1440, which 0.8.9 drew without smoothing, are now smoothed too. The game's own tick takes about half the time it did, which helps big battles in every view. (0.8.10)
• Mac players install 0.8.10 by hand. Mac players, those on 0.8.9 included, install 0.8.10 by hand, from the .pkg. The game offers the update itself on Windows, Linux and the Steam Deck. (0.8.10)
• Fixes. 3.1c's menus, the in-game menu and the load dialog draw letters their fonts lack, such as ç, ã and õ, in the modern fonts, where they showed a box. On macOS, the system's pointer no longer shows beside the game's cursor when the game opened behind another program or lost the focus while a match loaded: over a window without the focus the system's pointer shows alone, and clicking into the window brings the game's cursor back. On macOS, the 3D view no longer takes ever more memory when its frames are copied back to the processor, as in recordings rendered to film and with a window renderer other than Metal, where the game dropped to a lower tier within a minute. (0.8.10)
• The speed keys, the order wheel and underwater explosions. The speed keys are back on the keys that type + and -, on AZERTY, QWERTZ and other keyboards, as in 3.1c, and the key editor names them as your keyboard labels them. The order wheel on a held mouse button lets the pointer move and lights the order under it; letting go on an order gives it, and any one click picks an order or closes the wheel. With Full hardware acceleration, explosions under the water keep their colours, such as a hovercraft's when it dies over water, which Underwater shimmer tinted like a sunken unit; the blast still goes off on the sea bed, as in the original game. (0.8.11)
• Computer players alone, and a tidier battle room. The host can start a multiplayer game against computer players with no other human. A room whose launch locks the options still waits for a second human, and the Start with One Human hack is retired. In a game started by a launch file or a launch option such as --player-limit, the battle room shows the host's version as 3.1 instead of 103.1, and its RES column only shows each player's screen size; change yours in Open Annihilation's settings under Graphics › Screen size. (0.8.11)
• Standing effects across the cores. Zoomed fully out, the standing effects of a big battle in the 3D view are now drawn across the processor's cores, and the ground the view keeps is no longer copied again every frame. (0.8.11)
• Mac players install 0.8.11 by hand. The in-game update for Macs was withdrawn in 0.8.11, so Mac players install 0.8.11 by hand, from the .pkg. Mac players install 0.8.12 by hand, once, and from 0.8.12 on Macs update in the game again. Players on 0.8.8 or older, on every system, install 0.8.11 by hand from the release's files; the game's update screen opens the release page for them. (0.8.11)
• Automatic updates are back on macOS. macOS automatic updates are fixed and back. Mac players install 0.8.12 by hand, once, from the .pkg; from 0.8.12 on, Macs update in the game again. (0.8.12)
• An update channel for Testing releases. Settings › Developer › Update channel lets a copy take Testing releases before everyone else; Stable is the default. (0.8.12)
• Invert the 3D camera and the mouse zoom. New in Settings › Controls: Invert 3D camera pan, Invert 3D camera rotation and Invert mouse zoom, all off by default. (0.8.12)
• The new settings in German, French, Spanish and Italian. The new settings and messages are translated into German, French, Spanish and Italian, the languages built into the game. (0.8.12)
• The faster graphics card on Windows laptops. On Windows laptops with two graphics cards, with NVIDIA Optimus or AMD switchable graphics, the game asks for the separate graphics card instead of the processor's built-in graphics, so it runs on the faster one. A choice you make in Windows' Graphics settings or in NVIDIA's or AMD's control panel still wins. (0.8.13)
• +stats names the graphics card. +stats names the graphics card that draws the 3D view, under the window's card, so you can see which card the game is using. (0.8.13)
• The first start after an update uses your own folders. The first start after an automatic update uses your own mods, maps, keys and settings; since 0.8.7 it could open with another folder until the next start. (0.8.14)
• The Boneyards are back. Total Annihilation's original online lobby is built into the game. Press ENTER on the Boneyards strip at the bottom of the main menu, or the B key, and log in with a Core Prime account; REGISTER opens coreprime.net/register for a player without one. The first entry installs the Boneyards from Core Prime, Cavedog's own lobby screens, art and sounds, about 1.5 MB, and later entries fetch them again only when Core Prime has a newer one, keeping your war map and settings. The lobby is as it was: the galactic war map with its planets and sectors, Recon, Chat, battle rooms, News, Ladders, your Profile and Help. QuickPlay finds a forming battle or hosts one, and the Locator finds a player; matchmaking follows in a later release. (0.9)
• Battles through Core Prime's relays. Battles launched from the Boneyards are played through Core Prime's relays, so nobody needs to forward a port and players in different regions can play together. They play 3.1c, Core Contingency or Battle Tactics, with no mutators. (0.9)
• Ready for online play. Before it opens, the Boneyards makes sure you can play online: it asks to turn on update checks and the content catalogue if they are off, asks you to update when a newer Open Annihilation is out, since the Boneyards needs the latest version, and switches a mod off for you, after asking first, because the Boneyards plays Total Annihilation without mods. Leaving the Boneyards offers to switch the mod back on. (0.9)
• The Boneyards on a mod's own menu. A mod with its own main menu shows a small Boneyards ENTER plate in its top right corner, and its own buttons stay where the mod put them; a mod on the base game's menu art shows the full strip. Mod authors can move or hide the plate in the mod's manifest, as the OAMOD standard describes, and the mods on Core Prime are updated with their places; those revisions need 0.9. (0.9)
• A faster megamap. The megamap opens at once the first time in a match, keeps the map point under the pointer when you roll off it, and draws faster while open, since the battlefield hidden under it is no longer drawn, with thanks to Silencer. (0.9)
• The Boneyards for programs. The MCP server (--mcp) reaches every Boneyards console, so a program can log in, chat and join battles. (0.9)
• The new messages in German, French, Spanish and Italian. The other language packs show them in English until their next revision. (0.9)

Release timeline, newest first

1. 0.9.06 Nov
   The Boneyards in the game: the galactic war map, chat, battle rooms, ladders and QuickPlay with a Core Prime account, and battles through Core Prime's relays; a faster megamap
2. 0.8.142 Nov
   The first start after an update uses your own folders
3. 0.8.132 Nov
   Windows laptops use the faster graphics card
4. 0.8.121 Nov
   Automatic updates fixed and back on macOS, which Mac players install by hand, once; an update channel in Settings › Developer for taking Testing releases first; Invert 3D camera pan, Invert 3D camera rotation and Invert mouse zoom in Settings › Controls; the new settings in German, French, Spanish and Italian
5. 0.8.111 Nov
   The speed keys back on AZERTY, QWERTZ and other keyboards; an order wheel on a held mouse button that works properly; explosions under the water keep their colours; a host can start a multiplayer game against computer players alone; the in-game update for Macs withdrawn until 0.8.12, so Mac players install by hand, as do players on 0.8.8 or older on every system
6. 0.8.1031 Oct
   Big battles drawn about 5x faster in the turned 3D view, with smooth turning and panning and the picture reaching the screen sooner; 4x edge smoothing that also covers wide windows such as 2560x1440; letters like ç and ã in 3.1c's menus; fixes to the macOS pointer and memory; Mac players install it by hand from the .pkg
7. 0.8.931 Oct
   Single-player and skirmish games pause while the window is away, with a setting to keep playing; Mac copies installed from the package update in place; updates install from the release's own packages; the update screens in the new look; a clear message when macOS refuses access to Documents
8. 0.8.831 Oct
   Big battles drawn about 10x faster in the turned 3D view and no stutter when the camera turns; a Double-click selects setting; GET MAP checks your game can play the host's map; the Mutators and Maps windows in the new look; fixes to building past the map edge, Windows names outside the code page, the key clash question and the Library's scroll
9. 0.8.730 Oct
   Any key for anything with a key editor and layouts that can be shared, a new look for Settings and the Library in Barlow, an updater with Roll back on macOS, Windows, XP and Linux, mods past 256 weapons and five sides, allied sight on the minimap; fixes to repairs, the minimap, fog, underwater features, Windows 95 saving and the 3D camera
10. 0.8.6.126 Oct
    Hotfix: gentler default levels for the graphics effects, nanolathe glow that no longer slows the game, coastal waves that show, right clicks without a stutter, the unit info panel as in 3.1c
11. 0.8.625 Oct
    Brains: computer players written in Lua for each computer seat, with Classic the first in a new Brains tab; a 3D camera with Full acceleration through Metal and Vulkan, coloured weapon lighting, nanolathe and wreck glow, heat distortion, water ripples and naval reflections
12. 0.8.523 Oct
    Mutators: 115 in a new Mutators tab of the Library and a MUTATORS button on skirmish, campaign and battle room setups; Shift ends an armed order as in 3.1c, Classic or Smooth fog of war
13. 0.8.419 Oct
    A mod side's order buttons work, mod settings for Cavedog's downloadable maps, queued buildings dragged to a new site with Shift, wrecks reclaimed on the sea bed, the Full tier on more graphics cards
14. 0.8.318 Oct
    Deep unit-script expressions as in 3.1c (Devolution's beacon), a third side's own panel art (Rumad), faster frames zoomed out; 22 mods in the Library
15. 0.8.218 Oct
    Computer players follow a mod's whole AI profile, silos stockpile nukes, saved games load in a fraction of the time, first-run setup carries on, Smooth motion setting; Argon, Total Mayhem and TA: Zero
16. 0.8.116 Oct
    Hotfix for Windows: the game finds its own language, registry and log files again
17. 0.8.015 Oct
    Rise of the Mods: the Library, over 3,000 maps, 14 mods, five new races, Ukrainian and Korean, Windows 95 with installers, first-run setup, launch files
18. 0.7.410 Oct
    Animated mission briefings, Full graphics in the biggest battles, a Steam Deck package, smaller programs, Windows 95 from source
19. 0.7.37 Oct
    A steady camera when following units, view past the map's edge, HUD scaling, computer players that build as in 3.1c
20. 0.7.26 Oct
    Simplified Chinese, Unicode chat, explosion flash, zoom to the whole map, every screen size
21. 0.7.15 Oct
    Steam Deck, .oamod installs, demo recorder playback and recording, every setting documented
22. 0.7.04 Oct
    Full hardware acceleration, mods, iPhone and iPad, five languages, modern text, files in Documents
23. 0.6.1 to 0.6.22 Oct
    Multiplayer over TCP/IP with the original protocol; data-file parsing matched to the original, historical bugs included
24. 0.61 Oct
    Windows XP, 32-bit and Raspberry Pi; up to 45% faster; deterministic across processors; aircraft as in 3.1c; no FFmpeg
25. 0.5 to 0.5.330 Sept to 1 Oct
    Signed macOS app and installer, smooth motion up to 120 fps, the settings dialog
26. 0.3 to 0.4.329 to 30 Sept
    First binary releases and launch-week fixes
27. 0.227 Sept
    Launch: single player on macOS, Windows and Linux, 29 years to the day after the original

Full notes for every version are on the releases page.

Current state

Roadmap

• Mods and mutators in the galactic war, in further releases of the 0.9 series.
• The full Matchmaking screen in the Boneyards, beside QuickPlay, in a later release.
• More of the community's mods in the Library.
• The rest of the single-player game, closing the remaining gaps against 3.1c.
• TA: Kingdoms and Iron Plague support.

Modding tools

Alongside the engine, Steve Gray has released Kbot, a full suite of modern, cross-platform modding tools for Total Annihilation and Total Annihilation: Kingdoms. Kbot is open source under the MIT licence and runs on macOS, Windows and Linux.

• One command-line tool that reads and writes the game's file formats: HPI archives, GAF and TAF animations, PCX images, palettes, bitmap fonts, TNT maps and map sections, 3DO models, COB unit scripts and TA: Kingdoms scenarios.
• Kbot Studio, a browser-based workbench for browsing, previewing and inspecting every asset in an installed copy of the game.
• A written reference for each of the game's file formats, and a Model Context Protocol server so AI assistants can work with game assets directly.

Source code: github.com/coreprime/kbot

The story

Steve Gray has been part of the Total Annihilation community for more than 25 years. He ran Planet Annihilation, one of the game's main fan sites during its heyday, and has followed the game through its patches, expansions and community mods ever since.

The idea of rebuilding the engine so the game could outlive Windows 95 first came up on a community forum more than twelve years ago. Like many such projects it stalled: reverse engineering a 1997 engine, its dozen file formats and its unit scripting language is a multi-year job for a single developer working evenings.

What changed is AI. Working with AI coding assistants, the author was able to turn years of accumulated community knowledge about the game's formats and behaviour, together with his own independent research into the game's network protocols and file formats, a personal project since 2014, into a working engine in a fraction of the time, while a growing test suite checks every part of it against the data and save files of an installed copy of the game.

How it was built

The engine was reverse engineered from the 1997 releases of the game and from the Boneyards-era updates of 1999 and 2000, released in the final days of Cavedog Entertainment. The file format handling that makes up much of the code was informed by community documentation dating back to 1997 and 1998, when modders first pried the game apart to build their own units and maps. That documentation was refreshed and updated as part of the Kbot project. The original executables were analysed with Ghidra, the open source software reverse engineering suite. The output of that analysis was not code but a set of specifications and tests describing how the game behaves, and the body of game logic was then implemented from those specifications, with Anthropic's Claude models, Fable and Opus, doing the bulk of the implementation under the author's direction alongside other tools, and the tests checking the result. The engine has grown to more than 1.7 million lines of code, and its test suite also checks it against the data and save files of an installed copy of the game.

Quotes

"I first remember opening PC Gamer magazine in 1997 and seeing a giant pull-out ad for Total Annihilation, an A3 sized single screenshot. 3D units, meaningful terrain and physics, and battles on a scale that other games didn't do. Ever since I've played Total Annihilation, tinkering with the game and its sequel, and being part of the game's community.

"The lack of source code for the game has challenged players and creators for decades, as limits with the technology kept getting in the way of ideas. After trying to get the multiplayer services working again over a decade ago, it was too time consuming so I parked the project. Fast forward to today, and with AI I was able to realise the project - and hopefully let Total Annihilation be enjoyed by a new generation of players."

Steve Gray, author of Open Annihilation

About Total Annihilation

Total Annihilation was released in North America on 27 September 1997 by Cavedog Entertainment, a division of Humongous Entertainment, and published by GT Interactive. Designed by Chris Taylor, it was followed by two expansions, The Core Contingency (1998) and Battle Tactics (1998), and by a stream of free downloadable units and maps from Cavedog, an unusual practice at the time. Its final official patch is version 3.1c, which Open Annihilation targets.

The game remains on sale with both expansions included. At the time of writing GOG lists the Commander Pack at $1.49. The original free demo is preserved on the Internet Archive and also runs in Open Annihilation, so anyone can try the engine without buying the game.

• Steam: store.steampowered.com/app/298030/Total_Annihilation
• GOG: gog.com/en/game/total_annihilation_commander_pack
• Free demo: archive.org/details/TotalAnnihilation_201405

Screenshots, video and logos

All images on this page may be used freely in coverage of the project. Screenshots show the original game's art, which belongs to its rights holders.

Screenshots

Every capture below is the engine running natively on macOS, window title bar included. Click any image for the full-size PNG.

Video

• Return of the Boneyards, the 0.9 trailer: youtube.com/watch?v=rl7NnpZCRv0
• The Atlas, over 3,000 community maps: youtube.com/watch?v=4pcekOr-3W0
• That ESCalated Quickly, TA Escalation: youtube.com/watch?v=n8RT6dgga-Q
• Super Senpai Lets Go, Rainbow Edition: youtube.com/watch?v=JwoZ6Zkp7Lo
• Uninvited Guests, five new races: youtube.com/watch?v=0GsYPjTZpEU
• 0.7 release trailer: youtube.com/watch?v=fQ2czvDkSSs
• 横扫千军 中文版 trailer, the game in Simplified Chinese: youtube.com/watch?v=S3lHzgbC2pI
• Launch gameplay video: youtu.be/kxtqmTNaTC8

Downloadable copies for embedding are available to press on request.

Logos

Source files for all logos: github.com/open-annihilation/branding.

Frequently asked questions

Is this legal?

Open Annihilation is a new engine that contains none of the original game's code, art, sound or data. It requires a legitimately purchased copy of Total Annihilation and reads the game's files from that copy at run time. It is not affiliated with, endorsed by or supported by the owners of the Total Annihilation trademark.

This is a well-established way of keeping classic games alive. OpenRA has run the original Command & Conquer and Red Alert assets in a new open source engine for well over a decade, and in February 2025 Electronic Arts went further and released the original games' own source code under the GPL. OpenMW does the same for Morrowind, OpenXcom for X-COM, OpenRCT2 for RollerCoaster Tycoon 2, CorsixTH for Theme Hospital, and ScummVM for hundreds of classic adventure games. In every case the player buys the original game, and the open engine gives it a future on hardware and operating systems its makers never saw.

Does it include the game?

No. Buy Total Annihilation on Steam or GOG, install it, and point Open Annihilation at the installation folder on first launch. To try the engine without buying the game, the original free demo from the Internet Archive works the same way.

How is this different from Spring or Beyond All Reason?

Spring and Beyond All Reason are new games inspired by Total Annihilation, with their own units, balance and rules. Open Annihilation runs the actual game: the original units, maps, campaigns, scripts and balance, from the original data files, with the aim of matching version 3.1c's behaviour closely enough that its save games load.

Why not just play the original?

On a current Windows machine the original can be made to work with community patches. On macOS and Linux it means Wine or a virtual machine, and on any platform high resolutions, modern displays and future operating system changes are a constant fight. A native, open engine removes that fight permanently, and gives the community a codebase it can fix and extend.

Does it work with mods and community units?

Yes. Community maps and units that use the game's own data formats work as they do in the original, and the engine plays full mods by their own rules: a mod describes how it differs from 3.1c in one profile file and the engine applies the standard hacks it names, with no code for any particular mod. Since 0.8 the Library installs them from signed catalogues, and Core Prime's catalogue already offers 32 mods, TA Escalation, Rainbow Edition and Great War At Sea among them, five new races, over 3,000 community maps and the Cavedog map packs and bonus units. Mods also install from a single .oamod file, and other catalogues can be added by address. Since 0.8.5 the Library also offers 115 mutators, small packages that change one game over the base game or any mod, switched on with the MUTATORS button on the skirmish setup, the campaign launch and the battle room; a mutator is a manifest, a short Lua script and the files it needs, and Modding Info on mods.coreprime.net explains how to make one. Since 0.8.6 the Library has a Brains tab for brains, computer players written in Lua and chosen for each computer seat, with Classic, the built-in computer player in Lua, as the first; Modding Info on mods.coreprime.net and the OABrain standard explain how to make one, and Classic's source is in open-annihilation/ai-brains. Since 0.8.7 a mod can have more than 256 weapon types and more than five sides, and a mod that does plays only between Open Annihilation machines. For building and inspecting content, the author's Kbot toolchain covers the same formats the engine reads.

What does it run on?

macOS 11 or later on Intel and Apple silicon, Windows 95, Windows from XP SP3 on 32-bit through current 64-bit Windows, and Windows 11 on ARM, each with an installer; Linux on x86-64 and ARM, including the Raspberry Pi; iPhone and iPad, built from source with Xcode since there is no App Store release; and, experimentally, the Steam Deck. The smallest supported machine has one Pentium III-class core and 256 MB of memory. The 3D view needs Full hardware acceleration, drawn through Metal on a Mac and through Vulkan on Windows 7 to 11 and Linux where the graphics driver offers it; Windows XP and 95 keep the classic view. On a Windows laptop with two graphics cards, NVIDIA Optimus or AMD switchable graphics, the game runs on the faster, separate card; a choice made in Windows' Graphics settings or in NVIDIA's or AMD's control panel still wins. On macOS, Windows, including XP, and Linux, Open Annihilation can update itself: it looks for a newer release every time it starts and every hour while it runs, installs one only when you say so, and keeps the version you had, with its settings, so Roll back in Settings › Updates puts it back. On a Mac, a copy installed from the package updates in place, and macOS asks for an administrator's password with its own prompt when only an administrator can replace the app. Settings › Developer › Update channel lets a copy take Testing releases before everyone else; Stable is the default.

Can I change the keys?

Yes. Since 0.8.7 every action in the game, in Open Annihilation's own screens and in the menus can take a key of your choosing, or a mouse button, in the key editor (Settings › Controls › Key layout › Edit keys…), which finds an action by the key you press and warns when two actions want the same key. A layout can be cloned, renamed and described, saved as an .oakeys file or copied as text to share, and the Library's Keys tab holds layouts. 3.1c's own keys work as they did, keys set with older key-remapping patches and tools carry into a layout of your own, and the keys overlay (Cmd+/ on a Mac, Ctrl+/ elsewhere) shows the keys you have in a match.

Can I play online?

Yes. Host or join a game over TCP/IP from the Multiplayer menu and set it up in the battle room; a map a player lacks is fetched from the battle room with GET MAP, which first checks that the player's game can play it and says what is missing, and the host's mutators with GET MUTATORS. A computer seat in the battle room can play the built-in computer player or a brain, and each brain runs in its own sandbox, so network games stay in step. The engine speaks the original game's protocol, so it can play with unmodified copies of Total Annihilation as well as with other Open Annihilation players. Since 0.9 the Boneyards, the game's original online lobby, is built in: press ENTER on the Boneyards strip at the bottom of the main menu, or the B key, and log in with a Core Prime account, which you can create at coreprime.net/register. The Galactic War, ladders for ranked play, news, chat and paging are there, QuickPlay finds a forming battle or hosts one through Core Prime's match queue, the Locator finds a player, and Boneyards battles are played through Core Prime's relays, so nobody needs to forward a port. The full Matchmaking screen follows in a later release.

Can I play mods in the Boneyards?

Not yet. Boneyards battles play 3.1c, Core Contingency or Battle Tactics, without mods or mutators, and the Boneyards switches a mod off for you, after asking, and offers to switch it back on when you leave. Further releases in the 0.9 series are intended to bring mods and mutators into the galactic war.

Can I contribute?

Yes. The source is on GitHub, the build takes a few minutes on any of the three platforms, and the README describes the layout and conventions. Bug reports from players who know the original game well are especially valuable.

Is all of it open source?

Yes. The engine is released under the GNU GPL version 3 and will remain free.

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Open Annihilation is a free, open source engine that plays the original 1997 strategy classic Total Annihilation natively on macOS, Windows, Linux, iPhone and iPad, and experimentally on the Steam Deck. It contains no game content and instead loads the maps, units, campaigns and save games from a copy of the game bought on Steam or GOG, including both expansion packs, aiming to match the final official release exactly. Its first release, on 27 September 2026, came 29 years to the day after the original game's North American launch. Thirty-five releases later, version 0.9 brings back the Boneyards, the game's original online lobby, inside the game, with a Core Prime account, the Galactic War, ladders for ranked play, news, paging and battles played through Core Prime's relays, and the 0.8 series, Rise of the Mods, added a Library that installs over 3,000 community maps, 32 mods including TA Escalation, Rainbow Edition and Great War At Sea, 115 mutators that change one game over the base game or any mod, computer players written in Lua, five new playable races and ten languages from signed online catalogues, on top of network play over the original game's protocol, full hardware acceleration with a 3D camera, a key editor that rebinds every action and an updater that can roll back, while still running on Windows 95 or a Raspberry Pi. It is developed by Steve Gray, a member of the Total Annihilation community for more than 25 years and the former owner of the fan site Planet Annihilation. Core Prime, the rebuilt Boneyards online service, is at coreprime.net. The engine is free software under the GNU GPL version 3. Website: play.coreprime.net. Source code and downloads: github.com/open-annihilation/open-annihilation

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