Zombie shooter games have existing years before the Resident Evil series and will continue to exist way after, so it doesn't rip off Resi just for having a zombie invasion in it. Resident Evil may be the biggest selling survival horror series of all time but it's not the instant go-to for zombie game ideas for developers. Lickers aren't the same as Smokers - I see the long-tongue resemblance but they're completely different zombies. Same with Crimson Heads and Witches - completely different. The co-op is also very different, the entire feel of the game is different. I think, aside from having undead as enemies and having the option to have 4 players, they're completely different game franchises altogether!!