Bugs...
I found some bugs...umm. Whenever i start a new game, the number of spaces a piece jumps side to side goes up by one. And each new game alternates between whether or not the pieces rotate. For instance, on the first game, it's a normal game of tetris, but on the second game, the pieces jump two spaces to the side instead of one, and the pieces don't rotate. And on the third game the pieces jump three spaces to the side, and the pieces rotate again. etc. etc. Other than this, i like what you did with it. Maybe put a button so you can hold a piece and swap it out later.