The nazi zombie mod is a nazi zombie mod, not a left 4 dead mod. You don't start at point A and have to get to point B to complete the level. Zombiecraft is also really nazi zombies in minecraft form.
What the topic creator was suggesting, was a mod more similar to the left 4 dead series, where you (maybe also some ai or some human players) can start at one point and travel through a couple of different levels till a finale. This means that the mod would also include random item/enemy spawn generation, special infected, etc.