Hmm what about, I dunno if anyones read it but The Fear series by Charlie Higgins, the people in it look and act like zombies but it only affects people over the age of 13, so teenagers, adults etc leaving kids uninfected. The people who are the zombies are smart, they hunt in packs, have different strengths some can run others can only shamble etc kinda like in Left 4 dead but some are smarter.<br/><br/>The virus has evolved in certain infected people to leave them with the ability to run, think, jump high, resist loads of damage and even speak. So what if we ignore the fact from teh book that it infects over 13's and just go with the idea of the virus evolving in certain zombies and them hunting in packs.<br/><br/>If not then I like Haibane's idea :D