Undertale is an indie role-playing video game released in 2015. It was developed by Toby Fox with additional art by Temmie Chang in the GameMaker Studio engine. The game received critical acclaim for its intuitive gameplay, themes, characters, and musical score.
Joel first streamed his playthrough of Undertale on 22 September 2015, a few days after the game's release. After beating the game the first time, he decided to go for the genocide route. Joel would later stream a playthrough for the game's spiritual successor, Deltarune, in 2018.