Huge congrats on your first successful gamejam !
Game was pretty clever, you got me good on level 6 :) There's a nice progression between levels, as mechanics are introduced at a very digestable rate. The theme was smartly integrated.
Small pointer for gamefeel, I would have liked being able to keep the key pressed when moving in a single direction. I didn't really like a few of the later levels, they felt a bit easy after level 6. Level 10 was neat and shows how this mechanic can be implemented in more complex levels.
The game felt complete with a small story, very accessible well explained controls, and a main menu. That's no small feat, be proud !
Lack of audio was not an issue for me, I prefer nothing to poorly implemented / uninspired stuff, and this kind of game doesn't really need audio anyways. Rated the audio 3 stars for this reason.