Neat demo, bad Tetris. As far as I can tell, you can only rotate one direction (use the up arrow), and fast-dropping instantly drops and locks the piece, so you have to wait ten seconds for it to slooowly drop if you want to slide it underneath another piece.
(Yeah, I know, I'm missing the point here. I'm kind of a Tetris snob.)
Getting Tetris right is extremely hard. There are so many tiny things to consider, e.g. timing stuff, fine grained controls, how blocks can be rotated when they are in a confined space... the list goes on.
Oh, absolutely. And a lot of those are choices to make and fine-tune rather than obvious boolean working/buggy issues. ie The Tetris Wiki lists a half-dozen different rotation systems alone, some of which show fairly complex behavior (http://tetris.wikia.com/wiki/TGM_Rotation). Add in getting the controls and timing just right, and a simple puzzle game becomes a lot trickier to pull off than it might seem.
Oh, and yours isn't all that bad. I played through an entire round without quitting out of boredom or frustration with the controls, which is better than I can say about a lot of random Tetris clones out there. Or maybe I'm just more forgiving of games that openly admit to being stupid and unoriginal ;)
(Yeah, I know, I'm missing the point here. I'm kind of a Tetris snob.)