This is a great concept!! I would love to see some more levels and enemies.
I think it's a missed opportunity that you don't keep your limbs when moving to the next level. I think that would have made it more fun since you'd be getting more powerful after each stage, and are now made up of a bunch of wacky parts.
The characters are very nice looking. They remind me of scribblenauts, which is cool and works perfect for this limb-swapping idea.
Great stuff!