I really liked your game, though I have some suggestions
1. I think it would make the game more interesting if game has multiple characters like Knight, Elf, Mage, etc for Player to choose and play from as I would be more like an RPG.
2. The Spider Boss can get really annoying so I think it would be more fair if you can stun or something.
3. The power ups would be a lot more useful in this game if you got more and more later on