OpenTyrian
Tyrian is an arcade-style vertical scrolling shooter. The story is set in 20,031 where you play as Trent Hawkins, a skilled fighter-pilot employed to fight Microsol and save the galaxy. OpenTyrian is a port of the DOS shoot-em-up Tyrian. Jason Emery generously gave the OpenTyrian developers a copy of the Tyrian 2.1 source code, which has since been ported from Turbo Pascal to C. The port uses SDL, making it easily cross-platform.