Very short game, as in, once it's game over you can only exit. I think I managed to dodge 27 or so demons before I got trapped by a sudden spike in demons.
It would be nice to have a Restart button on game over, to give the game another try. Also, maybe consider a gentler difficulty curve. At the start each demon wave had 1 or 2 enemies. Then the next step up was 5 demons at once.