OpenRA
OpenRA is a free and open source real-time strategy game engine that reimplements early Westwood Studios classics. Written in C using SDL and OpenGL, it supports official mods for Command & Conquer: Red Alert, Command & Conquer: Tiberian Dawn, and Dune 2000. The engine runs on Windows, Linux, BSD, and macOS, offering modernized gameplay with features like unit veterancy, building queues, and fog of war while preserving the original feel. Players can engage in single-player skirmishes and missions or compete online through multiplayer matches and dedicated servers. OpenRA includes comprehensive modding tools, allowing users to create custom maps via a built-in editor, script missions with Lua, design their own RTS games using YAML-based trait definitions, and share creations through the community resource center. Distributed under the GNU GPLv3, it is not endorsed or supported by Electronic Arts.