Undertale – Indie RPG by Toby Fox
Every monster in the Underground has something to say, and the way the player answers shapes the rest of the trip. This top-down RPG sends a fallen child through the Ruins, Snowdin, Waterfall and Hotland, with puzzles to solve on the way and a turn-based fight whenever a hostile monster shows up.
Top 3 Reasons to Play
Fights that can be talked down. Alongside the usual attack command, each encounter offers non-violent options, and the whole game can be cleared without killing a single enemy. Dialogue, characters and the story itself change with the player's choices.
A score that reuses its own melodies. Composed in FL Studio, the soundtrack ties motifs to characters and brings them back in altered form. “Hopes and Dreams”, the last boss theme on the pacifist route, stacks most of those tunes into a single track.
A second playthrough that remembers the first. Boss dialogue on a repeat run responds to what happened in earlier ones. The same metafictional streak runs through the writing and the mechanics.
Story and Lore
Long before the game begins, humans and monsters fought a war, and the monsters ended up banished to the Underground, a large region beneath Mount Ebott. A magic barrier seals it off from the surface. The only opening is a gap on the mountain itself, and a human child tumbles through it at the start.
The first face waiting below belongs to Flowey, a talking flower who explains how battles work and hides worse intentions than his manner suggests. Toriel, a motherly goat-like monster, pulls the child out of that first encounter, teaches them to get through conflicts without killing and wants to adopt them. She also wants to keep them away from Asgore, king of the Underground, whose castle holds the barrier and with it the way out.
Asgore's interest in the child comes out along the way: he has gathered six human souls from earlier visitors and needs one more to break the barrier. That makes the child the missing seventh.
The road there starts in the Ruins, where the fall ends and Toriel waits. It continues through Snowdin, a snowbound forest patrolled by the skeleton brothers, then the mushroom-lit stretches of Waterfall, which hide a Temmie Village, and finally Hotland, where Alphys guides the child by phone toward the CORE.
Gameplay and Mechanics
Between fights the game runs as a top-down adventure, with towns and caves to cross and puzzles and vendors along the way. Battles begin from scripted events or random encounters and move to a separate screen where the player's SOUL appears as a small heart.
The player's turn has four commands. FIGHT relies on a timed button press. ACT checks an enemy's stats and opens actions that differ from monster to monster. ITEM opens the inventory, and MERCY offers Spare or Flee. A spare unlocks after the right ACT choices or after wearing an enemy down without finishing it, and a handful of boss fights end only once the player survives until the opponent has finished talking.
Enemy turns are dodging phases in the bullet-hell tradition. Fox has cited the Mario & Luigi series and the Touhou Project as influences on this half of the system, and attack patterns shift depending on how the player treated the monster. Colored obstacles add rules of their own: cyan attacks are avoided by standing still, orange ones by moving.
The heart also changes behavior from fight to fight:
- Red is the default, with free movement in every direction.
- Blue adds gravity, so jumping takes over as the main way to dodge.
- Green pins the heart in place while a shield blocks incoming spears, the setup Undyne's fight relies on.
- Purple restricts the heart to a set of lines.
- Yellow lets the heart shoot back, which is how Mettaton EX is fought.
Defeated enemies pay out gold and EXP, but grinding is never required to progress; Fox deliberately kept it optional. What the player does to monsters sorts the run into one of three endings. Finishing after fighting some monsters, or none, gives the Neutral ending. Finishing without a single kill and then reloading the save opens the True Pacifist ending. Clearing out every fightable monster, by repeating random encounters in each area until none remain, leads to the Genocide ending, also called No Mercy.
Characters and Factions
The skeleton brothers Sans and Papyrus act as sentries near Snowdin and are named after the typefaces Comic Sans and Papyrus, which their dialogue boxes also use. Sans later became a Mii Fighter costume in Super Smash Bros. Ultimate, and his boss theme, “Megalovania”, was already in use in Homestuck and in one of Fox's EarthBound ROM hacks before this game. Papyrus began as a notebook sketch of a meaner character called “Times New Roman”.
- Undyne: by Fox's account, the first boss he wrote to want the child dead.
- Alphys: first drawn as a man, then redesigned as a woman with eyelashes added.
- Mettaton: the robotic TV host Alphys built; his EX form can be spared by pushing the show's ratings high enough.
Off the main road, Muffet runs a Hotland bake sale where every item costs 9999G, and Tem keeps a shop in Waterfall's Temmie Village, where money can go toward college tuition. Frisk is the child the player controls, named only once the story reaches its late reveals. Chara is the first human to fall into the Underground, and their part in events is best left for players to uncover.
Two camps frame the setting: the monsters of the Underground, ruled by Asgore, and the humans beyond the barrier. Inside the monster kingdom, the Royal Guard handles defense under Undyne, and Alphys serves as royal scientist.
Editions
On PC there is a single edition of the game itself, the standard release. Steam also lists a bundle that adds the soundtrack, which is otherwise a separate purchase there.
Console ports were handled by the localizer 8-4 and differ in small ways:
- PlayStation 4 and PS Vita add the Dog Shrine area and trophies of their own.
- The Nintendo Switch version has a boss fight against Mad Mew Mew that appears nowhere else.
- The Xbox One and Xbox Series X|S release includes a slot machine in the Dog Shrine.
Physical copies exist as well. Fangamer published a retail PS4 version and a collector's edition for Switch, both boxed products separate from digital keys.
For the tenth anniversary in September 2025, Fangamer and Toby Fox streamed a modified build with new dialogue, areas and boss fights. The new battles were released as a browser game, and the new music and art assets became available to download.