OpenRA is a libre, free and open-source real-time strategy game engine written in C# with SDL and OpenGL, built for players, mappers and modders who want to run and extend early Westwood classics such as Command & Conquer: Red Alert, Command & Conquer: Tiberian Dawn and Dune 2000 on Windows, Linux, *BSD and Mac OS X.

What it is

OpenRA is a cross-platform real-time strategy game engine hosted at openra.net and developed on GitHub under the GPL-3.0 licence. It is written in C# and uses SDL and OpenGL for its platform and rendering layers, which lets one codebase run on Windows, Linux, *BSD and Mac OS X. Rather than shipping a single game, it ships an engine plus a set of distributed mods, including reimaginings of Command & Conquer: Red Alert, Command & Conquer: Tiberian Dawn and Dune 2000. EA has not endorsed and does not support the product.

The concrete thing OpenRA replaces is the original per-title engine code for those games: instead of a separate proprietary engine for each Westwood release, OpenRA offers one libre engine that carries the classic titles as mods and adds modern tooling around them. That tooling includes a dedicated game server, a Lua API for scripted missions, YAML-based gameplay definition with auto-generated trait documentation, and a published mapping and modding workflow. The repository is large and active, with roughly 17,400 stars, 3,000 forks and hundreds of contributors filing and fixing issues.

Key capabilities

• A single C# engine built on SDL and OpenGL that runs on Windows, Linux, *BSD and Mac OS X.
• Distributed mods that reimagine Command & Conquer: Red Alert, Command & Conquer: Tiberian Dawn and Dune 2000.
• A Lua API for scripted missions, documented at docs.openra.net.
• Data-driven gameplay defined in YAML files, with auto-generated trait documentation to get started.
• A Dedicated Game Server that can be set up immediately for hosting multiplayer matches.
• Mapping support: an official Mapping tutorial, custom rules that change gameplay drastically, and map sharing on the OpenRA Resource Center.
• Mod development through the OpenRA Mod SDK (OpenRAModSDK) and the Modding Guide, with total conversions uploaded to the project's Mod DB profile.

Who uses it and how

• Players of the reimagined Red Alert, Tiberian Dawn and Dune 2000 mods, who use the "Playing the Game" guide to win multiplayer matches.
• Modders and total-conversion teams, who download the OpenRA Mod SDK and follow the Modding Guide to create their own classic RTS.
• Mappers, who change gameplay with custom rules, script missions with the Lua API, and upload their maps to the OpenRA Resource Center.
• Server operators and community hosts, who run a Dedicated Game Server or sponsor a mirror server if they have bandwidth to spare.
• Contributors, who read INSTALL.md, follow the Contributing guidelines and Code of Conduct, and coordinate through #openra on Libera, the Discord, and the forum.

Getting started

The README names no package or container image: it directs builders to INSTALL.md and the Compiling wiki page for setting up an OpenRA development environment. Hosting is covered separately by the Dedicated Server wiki guide.

How it compares

The facts provided name no comparable tools and no paid products that OpenRA replaces, so it stands alone in this registry; the only commercial products referenced are the Westwood titles it reimagines, which come from EA and are explicitly unsupported by that publisher.

When to use it — and when not to

Self-hosting means operating a Dedicated Game Server, and building from source requires a C#/.NET, SDL and OpenGL toolchain rather than a single installer. Because the licence is GPL-3.0, teams that need to keep engine modifications proprietary should look elsewhere. The README itself is thin and defers to the wiki, where the Hacking overview is described as "now very outdated", and the tracker carries around 1,598 open issues — so expect to read documentation closely and contribute fixes rather than wait for them.