Deltarune is an episodic role-playing video game created by American indie developer Toby Fox. Set in a parallel universe to his 2015 game Undertale, it follows Kris, a human teenager predetermined to save the world alongside Susie, a monster, and Ralsei, a prince from the Dark World. Throughout the story, the party establishes relationships with a variety of allies and opponents. The combat system is turn-based and uses bullet hell mechanics. Like in Undertale, enemy encounters can be resolved peacefully or through violence. The game shares several characters and gameplay elements with Undertale, but takes place in a separate setting and features an overhauled battle system with multiple party members.
The inspiration for Deltarune came to Fox in a fever dream in 2011. Development initially began in 2012, but was abandoned before Fox created the first room. Temmie Chang, who had assisted with character art in Undertale, serves as the main artist. After the release of the first chapter, Fox expanded the team to assist with development.
The first two chapters were released as free demos in 2018 and 2021 respectively, while the third and fourth chapters were made available in 2025 with the game's paid release. The fifth chapter was released as a free update in June 2026, with the sixth planned for 2027 and a seventh planned for a later release. Initially released for macOS and Windows, it was later ported to the Nintendo Switch and PlayStation 4 in 2019, followed by the Nintendo Switch 2 and PlayStation 5 in 2025. The game has been praised by critics for its soundtrack, characters, narrative, and sense of humor.
Gameplay
Deltarune is a role-playing video game with a top-down perspective. The player controls a human named Kris Dreemurr and has a party of other characters who they select actions for during battle. The game features both overworld and combat sections. In the overworld, the player can solve puzzles, collect items, and interact with characters and the environment. Different chapters introduce unique traversal mechanics, such as climbing, or statues that shift the game into a 2D platformer with action-based combat. Unlike Undertale, Deltarune does not have a random encounter system; instead, players can see the enemies in the environment before they encounter them, allowing for the possibility of avoiding or deliberately initiating combat.
The game uses a turn-based combat system, where players can choose from a set of actions each turn: fight, act, item, spare, and defend. As in Undertale, players control a heart-shaped soul in a fixed area and must dodge enemy attacks in the form of bullets, though the exact mechanics are sometimes unique to the respective enemy. Defending or "grazing" an incoming attack by letting it come close to the heart without getting hit by it increases the tension points (TP) gauge, which allows party members to use spells or special abilities. For example, Ralsei can pacify tired enemies with a spell.
Players may use acts and spells to spare enemies non-violently. The second chapter introduced the ability to use this strategy to recruit enemies to live in the player's Castle Town. Alternatively, fighting an enemy, which also increases TP, can lead to them being defeated violently. Starting in chapter 2, defeating enemies violently causes party members to gain HP and magic power after the battle ends, but enemies defeated this way cannot be recruited for the rest of the chapter.
Plot
Deltarunes narrative spans seven chapters, of which five have been released. Although it features characters and elements from Undertale, it takes place in a parallel universe distinct from that game's setting.
Chapter 1 – The Beginning The game begins with a voice prompting the player to create an avatar, but the "vessel" is ultimately discarded, as "no one can choose who they are in this world." Instead, the player is given control of human teenager Kris Dreemurr, who arrives at school late. After being paired with their delinquent monster classmate Susie for a group project, their teacher Alphys sends them to get supplies. However, they fall into a strange realm within the supply closet, called a Dark World, where they meet the dark prince Ralsei. He welcomes them to his empty Castle Town and tells them of a prophecy, in which they are three heroes destined to seal the geyser-like Dark Fountains that sustain the Dark Worlds. A new Dark Fountain has created a Dark World next to Ralsei's, ruled by the tyrannical King, and threatens to upset the balance between the Light and Dark Worlds. An uninterested Susie joins King's son Lancer in opposing Kris and Ralsei, but both are eventually convinced to change sides and join the party.
Unwilling to confront his father or see his new friends hurt, Lancer betrays the party and imprisons them in King's dungeon. After freeing Kris and Ralsei, Susie fights Lancer, but reconciles with him and promises not to hurt King. The three confront and defeat King, who remains unrepentant even after being spared. After sealing the Fountain, Kris and Susie wake up in an unused classroom filled with objects resembling the Dark World's inhabitants. That night, after returning home, Kris rips out their soul (represented as a red heart and directly controlled by the player), locks it away, and draws a knife.
Chapter 2 – A Cyber's World The next morning, Kris's mother Toriel scolds them for eating her pie with the knife. After sleeping through class, Kris and Susie return to Castle Town, where Ralsei instructs them to retrieve the objects from the unused classroom to restore their Darkner forms. He then sends them away to focus on their school project with classmates Noelle Holiday and Berdly. However, they discover a new Dark World within the library's computer lab ruled by a laptop Darkner named Queen, who has recruited Berdly to her side and kidnapped Noelle. After reuniting with Ralsei and Noelle, the party splits up, and Kris and Noelle rekindle their childhood friendship while evading Queen and Berdly.
Queen betrays Berdly and captures everyone, but Kris and Susie escape and convince him to join the party. They confront Queen, who reveals that the Dark Fountains were created by a mysterious figure known as the Roaring Knight; she intends to force Noelle to open another Fountain for her, something any Lightner can do. She attacks the party with a giant mech, but they eventually convince her to stand down. Berdly attempts to create a Fountain for Noelle, but Ralsei warns everyone that opening too many Fountains will cause the prophecy's apocalyptic Roaring.
After Kris seals the Fountain, the four awaken in the computer lab, and Noelle and Berdly dismiss the adventure as a dream. Kris heads home, and Toriel invites Susie to spend the night. While Susie and Toriel are occupied, Kris rips their soul out of their chest, locks it in the bathroom, and briefly leaves. After they return, Toriel finds her car tires have been slashed and calls the police. Once everyone falls asleep, Kris removes the soul again and creates a Dark Fountain in the living room.
Chapter 3 – Late Night Kris and Susie awaken in the new Dark World, where Ralsei attempts to dissuade them from becoming too attached to him or other Darkners, since they are all unreal alternate manifestations of everyday objects. As Susie attempts to convince him of his worth, they are interrupted by Tenna, a Darkner created from Toriel's old television. The party agrees to star in his game shows, but they eventually sneak off the set and find a sleeping Toriel held hostage. Despite their protests, Tenna refuses to stop the games and allow them passage to the Fountain. Feeling abandoned and obsolete after the Dreemurr and Holiday families drifted apart, he explains that the Roaring Knight promised him relevance in exchange for keeping the Fountain open. After the party defeats Tenna, Ralsei and Susie comfort him, promising to help him find love and appreciation in another household.
Touched, Tenna agrees to return Toriel and let them seal the Fountain, but he is suddenly attacked by the Knight. The Knight defeats the party and attempts to capture Toriel, but is foiled by police officer Undyne, who had entered the Dark World responding to Toriel's previous call. After the Knight abducts Undyne, Kris and Susie pursue them across the Light World to Hometown's old emergency shelter, which houses another Dark World. The door shuts before they can enter, and they discover the bunker's lock requires three numeric codes. After resolving to find the shelter codes and save Undyne, Susie returns to the Dreemurr home, and the bunker door opens for Kris.
Chapter 4 – Prophecy Kris and Susie go to church with Toriel the next morning after sealing the living room Fountain, and conclude that their best lead on the bunker codes is Noelle's mother, Mayor Carol Holiday. While investigating Holiday Manor, Susie distracts Noelle as Kris finds a code inside the guitar of Noelle's missing older sister December. However, they rip out their soul before it can be read. The player-controlled soul enters the ventilation system and overhears Kris calling an unknown person, who instructs them to prevent Susie from finding the guitar. Kris fails to stop Susie and Noelle from playing the guitar and takes back the soul, but Carol returns home and expels Susie before she can discover the code.
Kris and Susie return to the church and find it transformed into a Dark World depicting the prophecy. They encounter a Darkner patterned after the deceased Lightner Gerson Boom, who encourages the party to defy their foretold fates. Ralsei ultimately breaks down and admits he has been hiding the true prophecy from Kris and Susie, including its tragic ending.
After adventuring across three Dark Worlds within the church, the party confronts the Knight, who opens another Fountain and creates a Titan, a monstrous harbinger of the Roaring. They defeat the Titan with Gerson's help, and, to Ralsei's horror, Susie accidentally sees the prophecy's ending. She smashes the image before the player can see, dismissing it as something the party would never let happen. They seal the Fountain and return home to find Toriel partying with the grocery store janitor Sans. An uncomfortable Susie leaves, and Kris later receives another phone call. As they climb out the window, the unknown caller reminds them of a mysterious promise.
Chapter 5 – Festival Day The next morning, Kris returns home to put the soul back in their body and finds the Castle Town Darkners preparing Susie for a date with Noelle at Hometown's Festival. After spending the day together, the two share a tender moment on the lakeshore, but Noelle leaves upon hearing that her father, Rudy, fell down while working on the lights. With Susie distracted, Kris removes the soul to create a Fountain inside their father Asgore's flower store.
Asgore is taken in by Flowery, a human-like "Plant" character formed from a preserved golden flower in his shop. While attempting to rescue him, the party encounters and befriends six more flower Plants who act as Asgore's servants in thanks for keeping them alive in the Light World. However, Asgore rejects the party's attempts to save him and instead obsesses over the truth behind the Fountains and the Knight, to the flowers' dismay.