Deltarune is a role-playing video game developed by Toby Fox. The player controls a teenage human, Kris, who is destined to save the world together with Susie, a monster, and Ralsei, a prince from the Dark World. During their quest to seal the "Dark Fountains" prophesied to end the world, the group meets the inhabitants of the "Dark World", some of whom try to stop them. The combat system is based on bullet hell attacks the player must dodge. Similar to Undertale, enemy encounters can be resolved peacefully or through violence.
Development of Deltarune began in 2012, three years before Fox's previous game Undertale was released. Though it shares some narrative elements with Undertale, including the fact that Deltarune is an anagram of Undertale, it takes place in a different setting. Deltarune's battle system was overhauled to more closely resemble the combat of the Final Fantasy series. The first chapter of the game was released for free on October 31, 2018, for macOS and Windows; the Nintendo Switch and PlayStation 4 editions were released on February 28, 2019. The second chapter was released for free on the same platforms in September 2021. More chapters are planned as a paid release, but no release date has been announced yet. The game was generally praised by critics for its soundtrack, characters, and sense of humor.
Deltarune's narrative spans seven chapters, of which two have been released with five more being planned for a later release. Although it features some characters and elements from Undertale, it takes place in a different setting.