Toby Fox begins developing the concept for Undertale, drawing inspiration from EarthBound, Touhou Project, and Mr. Bean. The core idea revolves around an RPG where players can choose to resolve conflicts without violence.

Spends two years primarily working on Undertale alone, handling programming, writing, art, and music. He launches a Kickstarter campaign to fund the game's development, which is successfully funded, demonstrating early enthusiasm for the project.

Undertale is released on Steam. The game quickly garners critical acclaim for its unique characters, heartwarming story, innovative gameplay mechanics, and memorable soundtrack.

Undertale becomes a commercial success, selling millions of copies and winning numerous awards. It is praised for its originality, humor, and emotional depth, establishing Toby Fox as a prominent figure in the indie game scene.