Well, I haven't added randomness to the zombie walk, but I added in lunging (sudden spurts of speed when they get close), and it seems to be just what this game needed! Thanks for the suggestion, it turned out great!

Sure thing, I could implement single player. I might even experiment a bit with AI for the second player. I think it's safe to say you have the record for the highest combo. :P

The problem with Greenfoot.start(), is that sometimes you have to wait a while before using the controls. I was wondering if you had found another way to do it without that, but I guess not.

The animations are made from pictures, one for each frame of movement. I know how to make them with code, but I wasn't planning to enter this in a contest, so I thought it wasn't worth the time.