Stratagus is a free cross-platform real-time strategy gaming engine. It includes support for playing over the internet/LAN, or playing a computer opponent. The engine is configurable and can be used to create games with a wide-range of features specific to your needs.
is a Warcraft II Mod that allows you to play Warcraft 2 with the Stratagus engine, as opposed to play it with the original Warcraft 2 one.
is a Starcraft Mod that allows you to play Starcraft with the Stratagus engine, as opposed to play it with the original Starcraft one.