Open-Source reimplementation of Westwood’s Command & Conquer: Red Alert game engine, updated to use the hardware acceleration of modern video cards using OpenGL and OpenAL for sound playback. It runs natively on Windows, Linux and Mac OS X. The game was designed with modifiability in mind, but is not identical to the original. Campaigns and mods made for the legacy game won't work out of the box.
Taking an old classic game and building a new engine around it to make it flexible and compatible with more than just the original game, this is a great example of reviving the old into a new game and giving it the chance to be more than the original.