Undertale makes mercy a mechanic — an RPG where every enemy can be spared

Undertale launched on September 15, 2015 with the tagline 'A traditional RPG where no one has to get hurt.' Toby Fox, who wrote, programmed and scored almost the entire game himself, had raised around $50,000 on Kickstarter — the campaign more than doubled its goal within a day — and the finished game ran about six hours.

Its subversion was structural: in a genre built on grinding and combat, every monster could be talked, joked, flirted or reasoned out of a fight. Fox told The Escapist that the talk system was inspired by Shin Megami Tensei, and that he wanted every monster to feel like an individual, because in most RPGs 'they attack you, you heal, you attack them, they die. There's no meaning to that.' The game's choices persisted across the save file, so how a player treated enemies changed the world, the endings and even the game's memory of the player.

Critics praised the subversive combat and emotional writing, and players amplified it through playthroughs, memes and fan art on YouTube, Twitch and Tumblr. Undertale sold over a million copies within a year of release and reached PlayStation 4 and Nintendo Switch by 2018, introducing the mercy mechanic to a much wider audience.

A decade later it is regarded as one of the most influential RPGs of its era: Inverse credits it with showing that deeply personal, idiosyncratic stories could resonate at mass scale, and with changing how the industry talks about player choice — sparing or ending an enemy became a statement about the kind of story the player wanted to tell.