What are some alternatives?
Tetris Blitz - Race against the clock in a two-minute blitz to clear lines and rack up points before time runs out.
Cuyo - An open source Tetris-style puzzle game for up to two players.
PureBlocks - PureBlocks is a minimalist falling blocks game for those who simply want to play.
NullpoMino - NullpoMino is an open-source action puzzle game that works on the Java platform.
Good Old Tetris - Play Tetris Online. The game that will never get old.