opentyrian – Google Code
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.
SVN builds are available on the forums for Windows and Mac OS X. Grab a copy of the Tyrian 2.1 data files (mirror), since they usually are not included with the SVN builds.
There are also console builds for the PSP, DS, GP2X, Gizmondo, GameCube, Amiga, Dreamcast, and Nokia Internet Tablets.