It's a shoot 'em up game, which works okay and barely has any bugs, but I'm not scoring higher because:
1. Barely any of the graphics is original. But at least it's excusable since there's only one guy making this, so I can't really blame them, not to mention that the blood graphics are just REALLY lazy, as there's just a pool of blood and blood coming out of the eye sockets, which I can get the pool, but why the eye sockets if I didn't shoot them directly by eye level? At least a blood splatter would be good enough.
2. The audio. It's not the worst thing, but why is the main music when you're playing this game only playing heavily on the right ear? Every time a Mario dies, it's always the same scream just pitched higher or lower. It's not bad, but why not go further by having MORE different screams?
3. The controls. I swear to God, if nobody on this planet can allow me to freely move within any axis the game gives me, it's plain AWFUL. If you're holding any key that goes horizontally, you can't move vertically and this works vice versa. What is this, a NES game? Also firing in this game is a semi-automatic, meaning you can't hold Z to fire. This isn't really a bad thing, because if Evil Skeleton is what I assume is holding a pistol, then why would I expect to hold Z to fire? But I don't know, the gun is barely visible and and you can't tell what model is it supposed to be aside from it being a pistol.