I'm pretty surprised that this topic has come this far, yet I continue to feed it... Brilliant!
My quick two cents: no zombies 'cause that's unfitting. Predators or a variant of! Like somebody said in here, Dr. Earnheardt's drugs could do some whacky stuff to people and maybe turn them into beasts or monsters. That'd be insanely epic and awesome to no ending extent.
Resistance to tyranny is obedience to God!
Far Cry is too realistic for zombies and monsters. Why not have something like survival mode on Call Of Duty. Where your on a map from multiplayer or have its own set of maps and you go through a series of waves as thhe people from the island ambush you and you have to survive. Allow us to be able to still drive vehicles and stuff and do whatever we can in single player and multiplayer.