This is a pretty straightforward Tetris game with just the standard, basic Tetris gameplay. However, what sets it apart from most other JavaScript Tetris games is the ability to play against your friends. Up to 4 people can play at the same time in a "last man standing" type of game. When lines are cleared in your own playing field, the speed of the falling blocks increase for your opponents.

A nice game if you're looking for some quick head-to-head Tetris action, although I must admit I'm not a big fan of the trippy background (holy acid trip, Batman). The source code is nice and readable (with comments) should you be interested.