I know it's entirely pointless to point out bugs to this, nor do I expect them to be fixed, but they do somewhat undermine the game's difficulty. Fun diversion besides that though.
The only way I could lose was being attacked by an enemy. I can shoot until 219 BPM. When I shoot once more, it gets kicked backwards to 217 BPM where it just stays regardless of shooting more.
Spacebar combines both Z and X commands at once, which seems unintended.