Tetris on a plane - Simple, open-source HTML/JS/CSS version of Tetris built as an exercise.
Hextris - An addictive puzzle game inspired by Tetris.
Good Old Tetris - Play Tetris Online. The game that will never get old.
Tetris Blitz - Race against the clock in a two-minute blitz to clear lines and rack up points before time runs out.
Blockinger - An open source Tetris clone for Android.
NullpoMino - NullpoMino is an open-source action puzzle game that works on the Java platform.