I really enjoyed playing this game! The graphics look great and i'm impressed that you were able to create the art and the game in such a short amount of time as a solo developer.
One thing I would note would be to make the first level (the one after tutorial) a little less challenging and to increase the key despawn time.
This was a fun play and it definitely fits the theme well, it's got a very retro feel to it.
Great Job!