The game mechanics are things the player interacts in the game that will aid you or make the game difficult.
(The following information points only to the first game)
The doors are used to ward off incoming animatronics, however, it will drain your power.
The Monitor, similar to Five Nights at Freddy's, is electronic equipment used to check where and possibly when the animatronics will reach your location.
The flashlight is used to check nearby surroundings that cannot be seen in the dark.