This actually looks like a decent game-mode! Will it ever be released to the public in the game-modes section?
I do need to give this a little criticism though. The build doesn't look like it fits with the concept (mostly meaning that it needs to be more gloomy and grity), and the heal areas don't make the gamemode more challenging. Also, why do you have a store when there is a random box? I feel that the store should be rid of while the random box stays. Also, the music shouldn't exist. Why not some ambiance to fit with the feel of the game? And you should only stick with one weapon set, like the L4D weapons you are using. Also, you should probably get rid of the health bars on top of them. It makes them 0.00001% more scary. Finally, you should be able to get outside of the build. You can probably ask someone else for help on how to keep yourself inside while the zombies can get in.
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