xtris is an open source tetris game for Linux. xtris v1.16 is a further development of the official version 1.15. I've added a game variant (speed mode). Moreover, a new stone appears immediately after the player pressed the space bar. Finally, a bug in the game server has been removed, which could be exploited to count a game won twice in multiplayer mode.
You can download the game here.
wtris is a German Windows client for xtris. xtserv and xtbot are included to the package, but they are effectively equivalent to the Linux version.