Neat little game. Made me think of a when I used to create puzzles in Paint as a child.
Needs some fixes though, like many people pointed out, otherwise it's a bit too annoying to play, proper collision between the pieces would be really helpful. Also, maybe, more features, to spice it up, like piece rotation and some obstacles.
Anyway, it'll be a fun and relaxing experience with some more work put into it, good luck.