OpenRA

OpenRA is a free real-time strategy engine that recreates Westwood Studios’ early classics. Its three included mods reimagine Command & Conquer: Red Alert (1996), the original Command & Conquer, known as Tiberian Dawn, and Dune 2000, using the original games’ graphics and sound.

Rather than copying the originals exactly, OpenRA keeps their look and feel while modernising how they play: the interface and controls follow later strategy games, units are rebalanced for online play, and it adds a modern multiplayer lobby, replays, observers and a map editor. The single-player missions of each game are included as well.

Because EA released Red Alert and Command & Conquer as freeware, OpenRA can download their content on first start, so those two need no original discs. A software development kit lets the community build entirely new games on the engine.