Ok, space key did the trick :) "L" no longer crashes. I found the game too hard, too many enemies and they have a lot of health. When I'm being attacked by 3 bats at a time, I keep dying. With less enemies, it might be playable and worth another shot. Please do continue to improve it and tune the game (or allow user to select easy/medium/hard difficulty.
The jumping effect (somersault) was really cool.