Blockinger - An open source Tetris clone for Android.
Tetris Blitz - Race against the clock in a two-minute blitz to clear lines and rack up points before time runs out.
Hextris - An addictive puzzle game inspired by Tetris.
Tetris on a plane - Simple, open-source HTML/JS/CSS version of Tetris built as an exercise.
1010! Klooni - 1010! Klooni is the FLOSS version of the original minimalistic puzzle game by Gram Games.
OpenBlok - A customizable, cross platform, open-source falling block game, packed with a bunch of features.