It really is a more difficult process than one might think, I didn't think that "just tweaking numbers" would take as long as I thought it would!
On a related note, I think the music I chose for the boss is pretty catchy (it isn't composed by me BTW). The boss also gets different attacks depending on the difficulty level selected, which I think gives the game some variety and replay value. Some of the attacks on higher difficulties are pretty weird though!
Anyway, I should have the game complete sometime this week, and I'll upload it to the showcase at that time.