Ahahahahahahahaha that ending.
The graphics are easily the best part of this game. Love the black-and-white palette. The audio is a close second.
The game itself seems to be a lot bigger than my screen. I'm not sure if that's actually the case, since I didn't have any problem beating it, but some enemies can wander outside the peripheral of the area, not to mention the game's logo on the start screen is partially cut off.
The punching mechanic seems to be, no pun intended, hit or miss. It seems inconsistent in the way that enemies can launch the first punch out of nowhere, even if you wield a punch on them first. I ended up winning only because I constantly spammed the Z key, which still caused me to lose health, but not as much.
The ending, though, was great. I'd love to see that actually be a cutscene/boss battle with the leader skull ninja. Plus a restart screen, as you've addressed in your bugs list. Overall, not bad for a jam entry.