An American music composer and video game developer, Toby Fox became known for his hit 2015 indie game Undertale, which evoked the sounds of 1980s arcade classics like Mario Bros. and Dig Dug with its score. Spanning orchestral and choral arrangements, playful computer music, rock guitar, and atmospheric sound effects, his diverse 2018 soundtrack for DELTARUNE, Chapter 1 landed on the Billboard Independent Albums chart. The sequel DELTARUNE, Chapter 2 reached the Top 20 of the Soundtracks and Heatseekers Albums charts in 2021.

Prior to Undertale's release in 2015, Fox had written music for Andrew Hussie's web comic Homestuck, a project he joined as a high school senior in 2009. About a child who navigates a monster-filled underworld while attempting to return to the surface, Fox's own Undertale was released for Windows and OS X in September 2015. It sold a million copies by the following April. Fox also wrote the electronic keyboard-based score for the game. Its soundtrack arrived on the Materia label in 2016. After CrazyGroupTrio released the 15-minute EP Undertale: Arranged on Piano, Iam8bit issued the more comprehensive Undertale on Piano in 2017. It featured pianist Augustine Mayuga Gonzales.

Fox went on to co-compose the score for 2017's Hiveswap, a video game based on Homestuck. The next year's DELTARUNE, Chapter 1 broke Fox onto the Billboard Independent Albums chart when his soundtrack for the adventure game peaked at number 41. A piano version by Torby Brand followed in 2018 and was in turn followed by a CrazyGroupTrio edition. Pokémon franchise composer Hitomi Sato arranged Fox's score for the 2019 Game Freak release Little Town Hero before Fox composed the music for the next year's Dweller's Empty Path (aka Escaped Chasm 2). It was developed by Undertale artist Temmie Chang.

Upon its arrival in 2021, Fox's original music for DELTARUNE, Chapter 2 went to number 11 on the Billboard Soundtracks chart and number 14 on the Heatseekers chart. ~ Marcy Donelson, Rovi