Great entry! The limited palette is pretty nice. I found myself wanting to struggle against the fragile code to get further in the game. I made it to the boss but died and didn't want to start over. The skulls and the skull explosions are pretty awesome, and the simple movement actually feels pretty good (especially that diagonal slash, which is a lot of fun to use). I would for sure play a version of this that had some issues ironed out.
Also, I liked the music too and I think it would be great with more variation.