A friend of mine is interested in running a campaign based on a comic book series called "The Walking Dead", which is basically a zombie story set in modern times. He asked me what game/rules system would be best suited for this type of game, and I really didn't know. I've never played All Flesh Must Be Eaten, but it looks pretty good. The group I play with is most comfortable with D20, but I don't think they will have any trouble learning something new. Is there any good D20 zombie books? If not D20, what can you recommend? Thanks in advance.