The Level Design is the best thing in this game. (Enemies aren't spammed, etc)
The sound effects are very good.(WAIT? You did them within the Jam Time?) (I don't know if this is a issue with WINE but there was no sound playing; I listened trough the audio files)
The Variable jump height would be a great benefit for this game and would make it much better.
Also putting actions on Z and X isn't good for people with non QUERTY-Keyboards. I would suggest using spacebar, alt and control for actions.