Star Control 2 Released Under the GPL
Jagasian writes "The classic computer space adventure role playing game known as Star Control 2 has been officially ported from its obsolete mono-platform source code to modern multi-platform C++/SDL source code. The game is open source, and compiles and runs on Linux! The alpha release binaries are available for download now!"
Must not forget Master of Orion (Microprose) and X-COM: UFO Defense (Microprose). Might as well throw in the whole Wing Commander series, too (WC1 & WC2 + their expansions, Privateer, Academy and Armada... leave WC3+ alone).
MOO, MOM, and X-COM are among my favourite games of all time... I still play all of them on a regular basis.