0 A.D. vs OpenRA vs Warzone 2100 — Best Open-Source RTS Compared

Real-time strategy is one of the few genres where open source genuinely competes with the commercial classics rather than just imitating them. Three projects stand out, and they take three completely different roads to the same destination: 0 A.D. builds a full-scale historical RTS from scratch, OpenRA rebuilds the Command & Conquer games people already love on a modern engine, and Warzone 2100 is a 1999 commercial RTS that was released as open source and has been modernised by its community ever since. All three are free, all three run on Linux, and all three are still being worked on. Here is how they actually differ, and which one deserves your disk space.

The Three Contenders at a Glance

• 0 A.D. — a complete, from-scratch historical RTS: build a city, raise armies, fight across antiquity. Release 28 “Boiorix” arrived in February 2026.
• OpenRA — not a new game but a new engine: Tiberian Dawn, Red Alert and Dune 2000 reimplemented in C# with modern controls, resolutions and online play.
• Warzone 2100 — the deepest tactics of the three: design your own vehicles from researched components and fight on 3D terrain where hills really do block line of fire.

If you want one sentence: 0 A.D. is the biggest and prettiest, OpenRA is the most familiar, and Warzone 2100 is the most mechanically interesting.

0 A.D. — Full-Scale Ancient Warfare

0 A.D. is the most ambitious of the three. Developed by the volunteer team at Wildfire Games, it is a genuine historical RTS in the Age of Empires tradition: you gather food, wood, stone and metal, expand a settlement, research technologies, and field armies of spearmen, archers, cavalry and siege engines. It is built entirely in the open — its own 3D engine, its own art pipeline, its own AI.

• Latest release: 0 A.D. Release 28 “Boiorix” (February 2026).
• Civilisations: a broad ancient roster — Romans, Athenians, Spartans, Persians, Macedonians, Carthaginians, Celts, Iberians, Han Chinese and Kushites among others — each with distinct units, buildings and technology trees.
• Gameplay depth: formations, counter-unit design, territory and building placement, siege warfare, and campaigns plus skirmish against a configurable AI.
• Multiplayer: online and LAN play through the in-game lobby, plus dedicated servers.
• Moddability: data-driven design and a JavaScript-based simulation layer mean total conversions are genuinely possible.
• Licence: GPL-2.0 for the code, CC-BY-SA 3.0 for the artwork — free software all the way down.
• Platforms: Windows, Linux and macOS.

The trade-off is development pace. 0 A.D. has been in development for well over a decade and is still honest about being an alpha — releases are infrequent but substantial. Download 0 A.D. — full details are on our 0 A.D. listing.

OpenRA — Classic Command & Conquer, Rebuilt

OpenRA solves a different problem. The original Westwood RTS games are still great, but they are painful to run on a modern desktop: fixed low resolutions, LAN-only multiplayer, awkward controls. OpenRA throws away the old engine and reimplements the game logic from scratch in C# with an OpenGL renderer, so you keep the gameplay and the maps while gaining everything modern.

• Three games in one download: Command & Conquer: Tiberian Dawn, Command & Conquer: Red Alert and Dune 2000 ship as official mods, with their original missions, units and factions.
• Mods are first-class: every game is a mod on the same engine, and the Mod SDK lets you build your own RTS on top of it.
• Modern controls: choose right-click or classic left-click, use hotkeys and production queues, issue Attack-Move orders, and set unit stances.
• Modern rendering: native widescreen and high resolutions with smooth zoom — no emulation layer, no hacks.
• Online play that works: built-in lobbies and matchmaking, replays, and an observer interface designed for streaming.
• Gameplay refinements: fog of war, capturable tech structures and unit veterancy bring the originals closer to contemporary RTS design.
• Latest releases: stable release-20250330 (March 2025), with an active playtest series — playtest-20261011 is the current release candidate.
• Licence: GPL-3.0. The original game assets are not part of OpenRA, but the engine can fetch them on first run where they are freely distributable, or use your own discs.
• Platforms: Windows, Linux, macOS and BSD from a single codebase.

If you grew up on Red Alert, this is the one to install first: everything you remember, running natively at 1080p. Download OpenRA — see also our OpenRA listing.

Warzone 2100 — 3D Tactics and Unit Design

Warzone 2100 is the odd one out, and that is exactly why people still play it. Pumpkin Studios released it in 1999 for Windows and the PlayStation, and in 2004 the source code and game data were released under the GPL. A volunteer team has maintained it ever since, and the modern build is a genuinely different game from the 1999 original.

• Design your own units: instead of picking a unit from a menu, you assemble vehicles from a researched chassis, a drive system (wheels or tracks) and a mounted weapon or support tool — then upgrade them as new technology unlocks.
• Real 3D battlefields: hills and buildings block line of fire, so elevation and cover actually matter.
• Sensors and counter-battery warfare: sensor towers and counter-battery sensors trace incoming artillery back to its source, so you can answer a bombardment in kind.
• Artillery-centred combat: long-range artillery, VTOL aircraft and anti-air defences decide assaults on fortified bases.
• Three-act campaign: the original 1999 story, from the Arizona deserts to Chicago and the Gamma base, rebalanced and playable at modern resolutions.
• Multiplayer: skirmish and team battles with up to 10 players, with dedicated-server support for long-running games.
• Latest release: 4.7.0 (April 2026), under active development.
• Licence: GPL-2.0-or-later for both code and the original game data, so the whole game is free.
• Platforms: Windows, Linux, macOS and BSD.

Warzone 2100 has the steepest learning curve of the three and the most unusual systems. Download Warzone 2100 — the details are on our Warzone 2100 listing.

Graphics and Presentation

0 A.D. wins on looks. It has a modern 3D engine with detailed unit models, animated buildings and a real sense of scale, and the art is the product of years of volunteer work. Warzone 2100 runs a 3D engine too, but its late-1990s low-poly models and angular textures are unmistakable — the terrain and lighting have been improved, the units have not been remade. OpenRA is deliberately 2D and isometric, because it is rendering the original sprites; what it adds is crisp high-resolution presentation, zoom and widescreen.

• Best looking: 0 A.D.
• Most faithful: OpenRA — the sprites you remember, sharpened.
• Most atmospheric: Warzone 2100 — the post-apocalyptic desolation still lands.

Content and Scale

0 A.D. is the biggest game here in raw content: multiple civilisations, dozens of building types, large maps and long matches that can run an hour or more. OpenRA is three complete games in one package, each with its own campaign and missions, though individual missions are short. Warzone 2100 sits in the middle, with a substantial three-act campaign and a technology tree that takes a full playthrough to explore properly.

All three are map-rich. OpenRA ships the map editor the developers use, 0 A.D. includes a scenario editor, and Warzone 2100 has a long-standing community map scene.

Multiplayer

Multiplayer is where OpenRA is furthest ahead. Its lobbies, matchmaking, replays and observer mode are the equal of a commercial release. 0 A.D. has solid online and LAN play with a built-in lobby and dedicated server support, but the player pool is smaller. Warzone 2100 supports up to 10 players in skirmish and team games with dedicated-server support, though big public games are often arranged through the community rather than found instantly.

None of the three requires an account with a vendor, a subscription, or a client that phones home. Hosting your own server is a first-class option in every case.

Modding

• OpenRA: the strongest story. Every shipped game is a mod, and the Mod SDK plus the C# engine make it practical to build a completely new RTS — several community projects have done exactly that.
• 0 A.D.: data-driven and scriptable, with an active modding community producing new civilisations and total conversions.
• Warzone 2100: the most approachable, because the unit designer is a modding tool built into the game itself — you can build custom units before you ever open the source.

AI and Single-Player

All three offer skirmish against AI opponents with adjustable difficulty, and all three have campaigns worth playing. 0 A.D.’s AI is competent at economy and raids but can be exploited; OpenRA’s AI is strongest in the classic missions, where the scenarios were designed around it; Warzone 2100’s campaign AI is scripted and scenario-driven, which is precisely what makes its 1999 missions still interesting. If single-player is all you want, Warzone 2100 and OpenRA give you the most structured content, while 0 A.D. is at its best in long skirmishes.

Licence and Platforms

• 0 A.D. — GPL-2.0 (code), CC-BY-SA 3.0 (art); Windows, Linux, macOS.
• OpenRA — GPL-3.0 (engine); Windows, Linux, macOS, BSD. Original game assets are downloaded separately where distributable, or taken from your own copy of the games.
• Warzone 2100 — GPL-2.0-or-later (code and game data); Windows, Linux, macOS, BSD.

There is no freemium tier, no in-game store and no advertising in any of them. You can redistribute every one of them, and all three are packaged in the major Linux distributions and on Flathub.

How to Choose

• You want the best-looking modern open-source RTS: 0 A.D.
• You want Red Alert or Tiberian Dawn again, but on a modern desktop: OpenRA.
• You want deep tactics, custom units and artillery duels: Warzone 2100.
• You have an old laptop: OpenRA is the lightest of the three; Warzone 2100 runs on almost anything with OpenGL, and 0 A.D. is the most demanding.
• You want to mod or build your own RTS: OpenRA’s Mod SDK, then 0 A.D.’s data files.

The Bottom Line

These three are not really competing for the same player, which is why the answer is easy. OpenRA is the safest recommendation: download it, and within ten minutes you are playing Red Alert at 1080p with working online multiplayer — nothing else here is that frictionless. 0 A.D. is the one to install if you want a genuine modern historical RTS and you are comfortable with a game that is still officially an alpha; the scale and the art are unmatched in open source. Warzone 2100 is the connoisseur’s pick: the unit designer and the counter-battery warfare give it tactical depth neither of the others reaches, and the whole game, data included, is free software. Install OpenRA tonight, keep 0 A.D. for when you have an evening to spare, and give Warzone 2100 a campaign run when you want something that plays like nothing else.

Browse the rest of our Games category — including the full directory of free and open source tools — or read Open-Source Minecraft Alternatives: Luanti vs Veloren (and More) for more open-source gaming. If we are missing a project you love, submit a tool and we will take a look.