Five Nights at Freddy's received generally positive reviews from critics, many considering it a frightening and distinct horror game.

Reviewers praised the atmosphere, sound design, and gameplay mechanics, although some found the jump scares repetitive and the game to have little replay value.

The player must complete their shift that lasts from midnight to 6:00 a.m. without being killed by the homicidal animatronic characters that wander the pizzeria at night.

[1][3][4] The player character, defenseless and confined to an office, is given access to a network of security cameras that provide views of various parts of the restaurant.

[8][9] The titular Freddy Fazbear character then appears playing the "Toreador Song", shortly before causing a game over unless the shift ends before he can attack.

[3] The security officer explains that the restaurant's four animatronic characters – Freddy Fazbear, Bonnie, Chica, and Foxy – are allowed to become mobile at night due to their servomotors locking up if they are left off for too long.

One of the voicemails mention "The Bite of '87", an incident which is implied to have led to the loss of a person's frontal lobe and forced animatronic mobility during the day to be prohibited.

Newspaper clippings viewable through the camera feeds reveal that a man reportedly lured five children into a back room and murdered them.

The restaurant later received complaints that the animatronics began to emit foul odors while blood and mucus leaked from their eyes and mouths.

The experience left Cawthon less inclined towards making Christian games, and he began production of the secular Five Nights at Freddy's.

[1] Nintendo Life found the controls to be easily accessible, and praised the game for making a tense mood apparent from the start.

[11] TouchArcade believed that the gameplay would feel lacking if the player was not scared by the atmosphere, and that its controls amounted to little more than "a game of red-light, green-light".

[3] GameRevolution considered the silence unnerving, and that the random sounds that occurred while playing complimented the atmosphere to make the experience tense.

[1] Gamezebo described the sound design as excellent, suggesting that players wear headphones not to just improve the experience, but to also detect the noises the animatronics made as they approached.

TouchArcade said that Five Nights at Freddy's challenged the player by forcing them to yield to their own paranoia, causing them to lose if they gave in to their fear.

[11] PC Gamer wrote that the game distinguished itself from the rest of the horror genre by relying not on jumpscares, but by pressuring the player with the possibility of one.

[4] Other reviewers considered Five Nights at Freddy's to be too reliant on jumpscares, which were effective at first but would become repetitive over time;[3][11] Nintendo Life said that the game's reliance on the scares and simple controls meant there was little replay value.

[33] The Five Nights at Freddy's community has developed a negative reputation online as a "toxic" fanbase,[34] but has remained an influential subculture on social media platforms such as TikTok and YouTube.

[22] Polygon later wrote that some of the fanbase had become primarily connected through fangame adaptations rather than the main media franchise, some choosing to play imitations rather than support Cawthon.