Here are a few ideas tossed around over on the Bash.
Walkers, Biters, Skin Eaters. I'm ready for some Governor Multiball!
Michonne multiball - decapitate 2 walkers, chop off their arms then establish a link.
What about Darryl? I'm sure he would have a killer mode. What would it be?
That would be Daryl's "Crossbow Hurry-Up"!
A video mode like on BSD but shooting walkers instead of wolves.