Tetrinet

Tetrinet is a PC based online multiplayer tetromino game, similar to Tetris, available as a free download. It is notable for its 12-block-wide playfield, which is wider than the average tetromino game's playfield, as well as its items, which players can use to attack other players.

TetriFAST
TetriFAST is a modification made to the original Tetrinet developed by St0rmcat. TetriFAST removes the 1 second delay between pieces, while keeping the other Tetrinet gameplay aspects intact.