This isn't your typical Five Nights at Freddy's clone game. Built entirely in Halo 2, this take on Five Nights at Freddy's makes the horror game a hell of a lot more combat-oriented.
As this video by RecklessRiley shows, the mini-game starts out with a phone call, just like the actual FNAF games do. And there is a security guard, who has a view of security screens that inform them of any animatronics that have spawned in that part of the level. Green monitors mean it's safe, blue monitors mean there's an enemy there.
Thing is, the animatronics are controlled by other players too. And if the security guard gets killed by the animatronics, they also get turned into an animatronic -- think of it as a variation on Zombie/Infection. Pretty clever, eh?
To combat the animatronics, the security guard can close doors, just like in FNAF. The security guard also has a shotgun and a magnum, and there are a variety of upgrades around the map that can help, too. I love the way the "Phone Guy" here explains this too:
"He didn't [use to have a shotgun], but then there was the playtest of March 10th... yeah. It's amazing that the human body can take that much teabagging from 12 year-old playtesters, all of whom who have done my mum, as a matter of fact."