The mark of any good puzzle game is that it takes a simple concept, and makes it work for a decent runtime - which is what you've done here. I really like the 1-bit graphics and the way the tiles shift slightly, which combined with the audio, makes the world feel delightfully strange and alien.
My only criticism is that I'd like the game to have given me an indication of how far through I was - apart from that, this is a very solid entry.