Toby Fox

On October 30, 2018, Fox tweeted a request for fans of Undertale to check the game's official Twitter account in 24 hours. The following day, Fox released the first chapter of the followup to Undertale, named Deltarune, for free under the guise of a “survey”. On November 1, Fox shared more details regarding the game, including that the rest of the chapters were expected to release simultaneously, but work had not yet started, and there was no estimated timeframe for completion. Fox also stated that he had been working on the project since 2012, and that the idea for Deltarune developed from Undertale during production. On June 12, 2019, as only the first chapter of Deltarune had been playable for several months, Fox expressed on his Twitter account he had hope he would complete the rest of Deltarune, saying: "Slowly I'm writing and drawing it all out." He stated that he has created "about 50 songs past Chapter 1."

In 2016, Fox released a number of unused musical tracks from Undertale. He also became a contributor to the A Profound Waste of Time magazine. Fox was then chosen to be part of the 2018 Games Forbes 30 Under 30 list for his role in creating Undertale.

Fox's most well-known work is the 2015 role-playing video game Undertale. The game sold more than 1 million copies, becoming a "breakout hit" and "pop-culture phenomenon". Fox worked on the entire game independently, besides the art assets—which he asked Temmie (Tuyoki) Chang to help with—to avoid relying on others. He had some experience in game development before Undertale, using RPG Maker 2000 with his three brothers to make role-playing games and EarthBound ROM hacks in high school, the most notable of which was Earthbound: The Halloween Hack. He thought of the character designs and ideas for Undertale while in college, where he drew them in his notebook.

Toby Fox studied environmental science at Northeastern University in Boston, Massachusetts. He started composing a variety of music for Andrew Hussie's 2009 webcomic Homestuck during his senior year of high school. Though he did not initially respond when Hussie started a "Music Contribution Team" in April 2009 and put up a news post asking musicians to participate, Hussie took note of his work when Fox started uploading piano covers of the webcomic's music on the MS Paint Adventures forums. Fox has composed music for the 2017 Homestuck video game Hiveswap, Undertale artist Temmie Chang's short narrative game Escaped Chasm, and Game Freak's 2019 RPG Little Town Hero, the last of which was arranged by Pokémon composer Hitomi Sato. He also composed a track for Pokémon Sword and Shield and the song "74" for Itoki Hana's PRAY album, in which he appeared as a guest singer.

Toby Fox (born October 11, 1991) is an American video game developer and music composer. He is best known for developing the game Undertale and the demo for his project Deltarune. He has also composed music for the webcomic Homestuck, as well as for the video games Hiveswap, Escaped Chasm, Little Town Hero, Pokémon Sword and Shield, and Super Smash Bros.. He is also known online as FwugRadiation or as Toby "Radiation" Fox.