I think grind-from-start games work better when you can do it faster on second try. The levels are really hard because I designed them after two weeks of playtesting and I find the first 10 or so to be relatively easy. If nobody passes level 6 I'm debating posting a video or livestreaming myself playing through the game so you can all see how far it gets.
EDIT: I think we didn't retest the levels after getting the AI to handle guns and bombs properly. I can't get past level 9.