I like it. Maybe the initial map was there because it was a guard station for the military HQ (this will give players a few, but not enough, weapons to start out). The map there will lead players to the real outpost, where they will find a map of the full facility and be able to locate the exit.
I have a nice visual of this. To one side, you can see the tops of buildings silhouetted in the night/setting sun and to the other is maybe a mountain or forest area, which would explain the river, the exit, and also give players a visual idea of where they are in the plant and how far from the exit they are (like the citadel in HL2).
Yea I like that idea. For the majority of the map, they can rely on melee weapons, found in various places, and pistols off of guards or a few weapons from the original guard post where they started. Near the end of the map, when they reach the military HQ, they can stock up on some better weapons, and consequently the end of the map can have a lot more zombies and be a lot more challenging, since they have better weapons.
Genius. I love it. Maybe to make it even more challenging, the zombies chase them into the room, where they have to barricade themselves in, but before the can initiate the process, maybe they have to flip a breaker through another passage way, but the majority of the people have to stay to defend the control room. That makes the team decide who should stay and who should go under pressure and make sure they don't send too many or too few.
The old "find a key to open a door" might be a little overplayed, but this could work. Maybe combine this with the thing I mentioned about about having to repair a fuse under pressure. Have the door locked and the key is on one of the few zombies in that confined area, so that it isn't impossible to find a key on the zombie if they don't know what they are looking for.
I don't know how well a big physics object like that would work in Multiplayer, but usually physics are jerky. This would be cool to get to work. Maybe have the pipe lifted above the players so the player just has to press a button in the crane and it starts lowering and gets stuck on a pile of crates or something else so that it's able to make the bridge for the players. I love the idea about how that one player is stranded then so that the other team members have to help them out. Maybe have it so that the ladder to the crane is right near the catwalk in the original position of the crane, but when the player moves it to crate the bridge, the ladder is no longer near a catwalk so he's stranded, that way, even if he lets the team over then moves the crane back to get up, the bridge has moved and he's stuck. The only possible way for the player to get over is if the team turns on the sprinklers to stop the fire.
I like the idea of having environmental things that players can use to take out groups of zombies. Maybe like in the old video of Ravenholm where the player roles a grenade under the big metal crate, which then falls onto a group of combine below, or the gas traps, or maybe just shooting a chain and having something fall on them. Make it so they aren't necessary to get by, but if used, ammo can be reserved and things will be easier later on.
Nah, this will work. I like working with industrial themed buildings rather than cities anyway. More interesting and better opportunities for cool effects.