After previously teasing something "Undertale"-related a day earlier on Twitter, Fox released the first chapter of "Deltarune", a game "intended for people who have completed "Undertale"", on October 31, 2018 for Windows and macOS for free. Fox said that this release is the first part of a new project, and considered the release a "survey program" to determine how to take the project further. Fox mentioned that "Deltarune" will be a larger project than "Undertale". He will release it as one game (not chapters) after forming a team to develop it. Fox plans for "Deltarune" to have only one ending.