"Undertale" is an indie role-playing video game created by Toby Fox. Released in 2015, the game gained widespread acclaim for its unique gameplay mechanics, compelling story, and distinctive art style. It's known for its emphasis on player choices and consequences.

In "Undertale," players control a human child who falls into an underground realm inhabited by monsters. The game allows players to interact with these monsters in various ways, including combat. One of the game's defining features is its "bullet hell" combat system, where players navigate through projectiles in a way reminiscent of bullet-dodging games.

What sets "Undertale" apart is its emphasis on player decisions. Players can choose to fight monsters or interact with them nonviolently, and these choices influence the game's narrative and characters. The game has multiple endings, including variations based on how players approach different situations and characters.

The game also incorporates humor, metafictional elements, and subversions of traditional RPG tropes, making it an experience that stands out in the gaming world. "Undertale" became a cultural phenomenon, praised for its emotional depth, memorable characters, and the impact of player choices on the story.