The pixel art is gorgeous and i smiled when noticed that the alien follows the UFO with its eye.
I think some levels can be solved in many ways, and probably skipped the intended solution in a couple or two. For instance, in level 3 i did not even know what the arrow block do because i was able to reach the music without it—i do not remember how, now; probably pure chance.
Having said that, there are a lot of levels for a three-day Jam, so maybe it is more that understandable.
My only minor complain is that i feel that it should be possible to use the keyboard in the menu too, especially for those of us that choose to use only the keyboard during the game.
The use of the limitation is spot on.
Very well done!