Thanks to Jonnection's RBoy Tracker, I can try to compose some music! (tomorrow, it was broken today )
Also, instead of Crabator II, how about Super Crabator, or Crabator's Revenge (If Crabator is a person)?
I'll suggest "Broken Legs" mode.
You cannot move, you have to survive an onslaught of enemies (forever/not forever), and hope that other weapons land close enough for you to reach.
Essentially, your character would be on the left, and the enemies coming from the right.
You could also have it so you have to risk an enemy getting close to you so that they drop stuff.