Nice implementation! I think there's a memory leak because the game crashed after a few minutes and the browser said it was using too much memory.
Feels pretty good. I think holding A to run and pressing X to jump would feel much better. Can you add a way to optionally swap that?
I love these. Will you also make then facing to the right horizontally at 0 degrees instead of 45 degrees?
The game crashed on Mac when I tried to hit the electric jelly fish with a torch.
