Hello. I think what you came up with is pretty cool. Here's some feedback:
* You can apply arrow key controls to WASD and Z to Space. Because most of the people aren't used to this.
* Sometimes we can't jump over the boss even with a double jump. That makes it very, very hard. You can change that.
* You should change the texture of diamondy-thing we loot from the monsters. It can be more pixelated to fit the other textures.