Marathon Mode and Play Stats
Complete all the levels in the game to unlock Marathon Mode and Play Stats for each world.
Zombie Skin is invincible
If you purchase and use the Zombie skin you will actually become invincible to all kinds of spikes and those black bubbling cloud things -however if you fall in those you can become stuck and have to reset (L + R). It doesn't seem the other skins have this feature.
King Costume...