Hey!! Nice work!
That's a good start and I'll come check it again once you added the other levels. But I can also suggest another very useful change:
not everyone uses a QWERTY keyboard and W+S is not very pratical for me (I use AZERTY, but there are still other layouts). Adding the Arrow keys as a substitute would be nice! (and would still count as a 2 button game, "synonym keys" are free =)).
Congrats!