Interesting, a pretty clever twist on Tetris. It did get me thinking about what the optimal way to play would be, as even setting up for a single tetris was pretty risky. So I dare say you balanced it well to set up the first challenge :)
The visual presentation is solid, but I'd like to see more happening in terms of effects and transitions. And there's plenty of room to grow in the music department (points for making your own sound effects!)