First we have a Bus Stop Maze of Buses, then a "museum" with some funny moments, then THAT ONE MAP, and then a finale in some weird random cave structure. In the museum, the melee weapons are bugged, and can crash the game when picked up. The third map offers the most teeth-grinding challenge of the campaign: you're basically in an arena with little to no cover, infected are attacking from all sides, and the elevator takes MILLENIA to arrive. And when it does, and your teammate(s) is (are) downed outside, you CANNOT just leave them behind, you MUST pick them up or kill them outright. The bots are particularly pathetic: when they're attacked from every side, they just stand there, losing hitpoints. And then you find youself in an odd cave (is THAT the Source of Infection?) and after the usual waves, a long run to the military chopper.