"F" is a term used by gamers and streamers as a sign of respect or mourning. It originates from a scene in the video game "Call of Duty: Advanced Warfare" where the player is prompted to press the "F" key to pay respects at a funeral.
Common Sense Media cautions parents, "While there's no graphic violence or gore, there are splatters of blood throughout the factory. Also, the horror nature of the game will likely be too scary for younger audiences."