The art is really well polished and the visual effects look great. You should definitely add some music to it though. I still awarded you 5/5 for polish.
The instructions were confusing. It took a moment to understand the way the directional blocks rotate. You should find a better way of indicating changes.
The one button rotation control is understandable given the game jam theme, but it really doesn't add to the game play. This game would be better off just using the standard a/d keys to rotate and w to move forward, for example. If you want to continue development post-jam, that's the first thing I would recommend.