UCN most commonly stands for "Ultimate Custom Night," which is an independent point-and-click survival horror video game in the Five Nights at Freddy's franchise. It was developed and published by Scottgames and features a customizable lineup of animatronic characters that players must survive against in a single night. UCN allows players to select and adjust the difficulty of numerous animatronics to create their own ultimate challenge.
In other contexts, UCN can refer to various things such as Ultracold Neutrons, a political party (National Civic Union in Bolivia), genes in the human urocortin family, or educational institutions like the University College of Northern Denmark.
The most prevalent usage of UCN in popular culture today, however, is associated with the Five Nights at Freddy's Ultimate Custom Night game.
