Wow! For a first submission, this is incredible! Also very, very difficult. :P Main thing I'd say is a pet peeve of my own, which is to include WASD as valid directional controls - it's easy to do, and helps those of us that don't have arrows on our keyboards (I had to do a remapping for this and a previous game, so it was okay, but still, easy to add in project settings under input). At some point I thought I was really kicking butt, and then I got absolutely nusted and wanted to start again to see how far I could get - that's a great sign for any game!
I can't wait to see more from you!