NullpoMino - NullpoMino is an open-source action puzzle game that works on the Java platform.
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.
OpenBlok - A customizable, cross platform, open-source falling block game, packed with a bunch of features.
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.