Yeah, I'm impressed with this one. I used backspace several times, and I entered a # whilst holding down the space key at least once - both of those work fine. I like the posture changes of the character while "he" is in the air.
I practiced enough now that I'm thinking you could tune it by making it harder as the score goes up. Tricky process though. You don't want to speed up a browser game too much, especially when the browser might be running on an older Raspberry Pi.