Tetris In 140 Bytes

"Is it possible to write a JavaScript program in no more than a tweet's length? A website called 140byt.es says it is and has an implementation of Tetris to prove it. Ok, it only has two types of block — hence its title "Binary Tetris" — and there's no rotate, but it works. The blocks fall down the screen and you steer them into place. You can try it out by playing the demo. Of course the real fun is in figuring out how it works and there is lots of help on the site — so if your bored how about the 140 character challenge?"