Back in the 80's

The flickering light is used within the left hallway, and all it does is simply toggling the visibility of a lamp on or off every 0.1 - 0.3 seconds.

The office door is used to block Animatronics from entering your Office. When you close the door, the power usage goes up, which will make the power go down faster. Both Office Doors have an increment for the power usage, the same happens when you turn on the hallway light.

The front door can be opened and closed to enter the building, however when entering the doors close behind you, which locks the door. By turned the CanOpenDoor boolean to False, it will lock the door so it can not be opened again.

Freddy Fazbear is 1 of 6 roaming characters in the game (Others being Bonnie, Chica, Foxy, Endo and Glitchtrap). He tracks the player with Pawnsensing, after which it turns the "In Range (Sees Player)" to true, untill he doesn't see you anymore. Freddy will then move towards the player, if Freddy is close to the player, he will jumpscare them, and it will be Game Over.

Most of the Animatronics have similar code, altho slightly different like better or worse sight, faster or slower walk speeds and some other parameters. There are also 4 animatronics that are slightly more unique.

Endo moves only when the player doesn't look at him, and he always knows where you are.
Angry Chica always knows where you are and is really fast (Easter Egg on Night 1).
Golden Freddy only has a door which you need to close, no Character AI used.
Foxy only becomes a physical character AI once he goes out of his cove, which you can click to keep him in it.