I think the zombies from RE4 in the beginning are not really zombies because the can talk and use things. They are really smart like humans, but they never died. But the head-crab zombies are zombies because they can infect people with their claws...maybe.
Why don't they let you have very high quality on XP? Why do they have to make you have to hack it? Plus there is not much difference so I guess it might be a marketing scheme.
siskokidd's comments