I would not say that this game is 'too easy.' Please don't make it for "veterans."
The reason is say this is that's it's fun to casually play around right now. Don't need it to be more frustrating.
Many thanks for all the tips. I've kept the levels in the game very small and that's why I've made it so that if you lose a life you have to start the level all over again. I loved that in the old games. Yes, it was annoying at times, but that's why I included the level codes. So you have to think carefully about whether I can kill the enemy with the arrows or whether I should jump on his head. That was always a challenge and I loved it.
The two buttons, one for jumping and one for shooting, should actually work