Undertales

Undertales is an informal, umbrella term used in online communities to refer to a broad range of fan-produced works that draw on the characters, setting, and themes of the indie role-playing game Undertale. It is not an official title, product, or separate canonical work.

Most Undertales content consists of fan art, fan fiction, fan-made games or mods, music remixes, and scholarly analyses that explore the game's narrative choices, morality, and humor. Community creators frequently engage with the game's Genocide, Pacifist, and Neutral routes, alternate storylines, and expanded lore, often adapting characters like Sans, Papyrus, and Toriel.

Undertale, released in 2015 by Toby Fox, has inspired a large online community and culture, with memes, conventions, and fan projects contributing to the game's enduring presence in internet culture. While Deltarune is a separate official game by Fox, it is often discussed alongside Undertale in fan discourse about the broader Undertale-inspired landscape.

Because Undertales is not a formally defined category, its usage varies among communities; some use it interchangeably with Undertale-related fan works, while others reserve it for a subset focusing on creative reinterpretations rather than direct fan fiction.