This is a survival map set in GLaDOS' chamber.
During normal gameplay, the map will open two gates to spawn more infected from, one all three minutes.
Every five minutes, a hatch on the floor opens to dispense supplies, up to four times.
While playing Versus Survival, the extra gates open in two minute intervals and the supplies are dispensed immediately.
The rate at which Common Infected spawn has been altered as well.
Usually, the horde respawn rate is 60 seconds at start, getting shorter by two seconds after each consecutive round.
But now, the interval starts at 50 and lowers by one second every round.
Except in Versus Survival. That one uses default spawn rates for CI.
Download: https://steamcommunity.com/sharedfiles/filedetails/?id=2967248662