I think there was a game on the c64 with similar or the same gameplay? was it called tapper or something?
Monkey Island mini games would be great!
A monkey island themed beat em up would be cool
fight through all the characters and of course, lechuck would be the final boss! each with their own weapons and hilarious finishers - Murray the demonic skull from monkey 3 can make an appearance... now who could refuse playing as him? biting and headbutting whilst hurling abuse
Try using different style graphics such as the ones used in the old Mortal Kombat games? or that could potentially ruin the feel of the game
anyway it was just a simple, basic, rough idea