Holy monkeys, Batman, you did this in a week? I'm floored! You did the focus and the theme flawlessly. You had a store and upgrades and everything. Even a lovely variety of enemies! Cute clean art style, really nice mechanics/ controls, and great fun! Even the spiny firey sword move is badass.
I also enjoyed that the enemies weren't the same every time you re-went through a room. Thats what I call polish.
I think the only thing I have to suggest is what everyone else has said: Magnetic pull for items, music loop, and MORE AWESOME CONTENT.
Congrats on a fabulous game!