Deltarune is a game that comes in parts, created by American indie developer Toby Fox. It takes place in a world similar to his 2015 game, Undertale. The story follows Kris, a human teenager, and their journey to save the world with Susie, a monster, and Ralsei, a prince from the Dark World. During the story, the group meets many allies and opponents.
The game’s fighting system is turn-based, meaning players take turns to act. It uses fast-paced shooting, like in Undertale. Players can choose to fight enemies or find peaceful solutions. Deltarune shares some characters and game features with Undertale but has a different setting and a new battle system with more characters on the player’s team.
Development of Deltarune started in 2012. The first two parts were released as free demos in 2018 and 2021. Parts three and four came out in 2025 with the full paid version. More parts are planned as free updates. The game was first made for macOS and Windows. Later, it was released for Nintendo Switch and PlayStation 4 in 2019, and for Nintendo Switch 2 and PlayStation 5 in 2025. Critics have praised the game for its music, characters, story, and humor.
Gameplay
Deltarune is a role-playing video game that is viewed from above, like looking down on a map. The player controls a human named Kris Dreemurr and chooses actions for a group of other characters during battles. The game has two main parts: the overworld and combat. In the overworld, players can solve puzzles, collect items, and interact with characters and the environment. Unlike Undertale, Deltarune does not use a system where battles happen randomly. Instead, players can see enemies in the environment before facing them, which lets them avoid or choose to fight them.
The game uses a turn-based combat system. Each turn, players can choose from these actions: fight, act, use an item, spare, or defend. Like Undertale, players control a heart-shaped soul in a fixed area and must avoid enemy attacks that come as bullets. However, some enemies have different attack methods. Defending or "grazing" an attack by letting it get close to the heart without being hit increases a gauge called tension points (TP). This gauge lets party members use spells or special actions. For example, Ralsei can use a spell to calm tired enemies.
Players can use actions and spells to spare enemies without fighting them. In the second chapter, this strategy can also be used to recruit enemies to live in the player's Castle Town. Alternatively, fighting an enemy increases TP and may result in the enemy being defeated violently. After a battle, party members gain health points (HP) if they win.
Plot
Deltarune's story is divided into chapters. Four chapters have been released, and three more are planned for later. Two of the upcoming chapters are currently being developed. While the game includes characters and elements from Undertale, it takes place in a different world that is similar but not the same as Undertale's setting.
The game begins with a voice asking the player to create an avatar. However, this avatar is not used because the story says no one can choose who they are in this world. Instead, the player controls a human teenager named Kris, who arrives at school late. Kris is paired with their delinquent monster classmate, Susie, for a group project. Their teacher, Alphys, sends them to get supplies. The supply closet closes behind them, and they fall into a strange realm called the Dark World, where they meet the dark prince Ralsei. Ralsei explains a prophecy stating that Kris, Susie, and Ralsei are heroes destined to close the Dark Fountains, which create the Dark Worlds. A new Dark Fountain has formed near Ralsei's world, ruled by a tyrannical king. Susie joins the king's son, Lancer, to fight Kris and Ralsei, but both Lancer and Susie later change sides and join the heroes.
Lancer refuses to hurt his father or his new friends, so he imprisons Kris and Ralsei in the king's dungeon. Susie frees them and fights Lancer, but she reconciles with him and promises not to harm the king. The three confront and defeat the king, who does not apologize. After sealing the Dark Fountain, Kris and Susie wake in an unused classroom. The room has objects that resemble characters, suggesting that Dark Worlds are reflections of ordinary rooms. Their inhabitants, called Darkners, are simply objects within those rooms. That night, Kris removes their soul (which the player controls), locks it away, and draws a knife.
The next morning, Toriel scolds Kris for eating pie and sends them to school. After sleeping through school, Kris and Susie return to the Dark World and reunite with Ralsei. Ralsei tells them to bring items from the unused classroom to the Dark World, restoring them to their Darkner forms. He then tells them to focus on their school project with classmates Noelle and Berdly. At the library's computer lab, they discover a new Dark World ruled by a computer named Queen. Queen recruits Berdly and tries to recruit Noelle. The group finds Ralsei, but they split up. Kris joins Noelle to help her avoid Queen's attempts to recruit her.
Queen captures everyone, but Kris and Susie escape and convince Berdly to switch sides before reuniting with Ralsei. Queen reveals that the Dark Fountain was created by an entity called the Roaring Knight and that she plans to force Noelle to open a Fountain, which anyone in the Light World can do. She threatens Noelle and the group with a giant mech, but they convince her to stop. Berdly tries to create a Fountain, but Ralsei warns that opening too many Fountains will cause an apocalyptic "Roaring."
Kris closes the Fountain, and the group wakes in the computer lab. Noelle and Berdly dismiss the events as a dream. Kris goes home, and their mother, Toriel, invites Susie to stay the night. While Susie and Toriel are occupied, Kris removes their soul, locks it in the bathroom, and leaves the house. Toriel finds her car tires slashed and calls the police. Later, Kris removes their soul again and creates a Dark Fountain in the living room by stabbing the floor with their knife.
Kris and Susie awaken in the Dark World Kris created. After reuniting with Ralsei, they meet Tenna, a Darkner made from Toriel's television, who convinces the trio to participate in game show segments. The group sneaks away and finds Toriel being held hostage by Tenna inside a giant toy capsule.
The group demands Tenna stop the games so they can seal the Fountain and return home with Toriel, but Tenna refuses. He explains that the Roaring Knight promised him relevance in exchange for keeping the Fountain open. After defeating Tenna, Susie comforts him, explaining that he has already brought joy and can find love elsewhere.
However, Tenna is attacked by the Roaring Knight, who also tries to capture Toriel. The group fights the Knight but is defeated until police officer Undyne arrives to rescue them. Kris and Susie chase the Knight through the Light World until they reach a locked bunker that appears to contain a Dark Fountain. The door shuts before they can enter, but they find a lock requiring three numeric codes. Susie returns to Kris's home to rescue Toriel. The chapter ends with the bunker door opening in front of Kris.
After closing the living room Dark Fountain, Toriel wakes Kris, and they go to church. They question townspeople about the bunker and conclude their best lead is Noelle's mother, Mayor Carol Holiday. At the Holidays' house, Susie distracts Noelle while Kris searches. In Noelle's sister December's bedroom, Kris finds a code in a guitar but removes their soul before it can be fully read. The player-controlled soul enters the house's ventilation system, where it finds Kris on the phone with an unknown person discussing the Knight's actions and instructing them to stop Susie from getting the guitar. Kris fails to prevent Susie from finding the guitar and returns the soul to their body. Carol returns home and expels Susie before she can memorize the code.
Returning to the church, Kris and Susie find it transformed into a Dark World with depictions of the prophecy. They reunite with Ralsei and meet an old man formed from the ashes of a dead Light World inhabitant named Gerson Boom. Ralsei admits he has hidden parts of the prophecy from Kris and Susie because he believes the truth would be too upsetting.
After exploring three Dark Worlds, the group encounters the Knight, who opens a Fountain, creating a "Titan" that signals the Roaring. They defeat the Titan with help from Gerson. Against Ralsei's protests, Susie sees the prophecy's ending, smashes it, and dismisses it as something the group would never allow. After sealing the Fountain, they return home to find Toriel drunk with the grocery store janitor, Sans. Susie leaves, and Kris, alone in their bedroom, receives a phone call from an unknown source. During the call, a promise between the caller and Kris, made earlier without the player's knowledge, is referenced.
In Chapter 2, players can choose an alternate path by making Noelle freeze every enemy encountered. Spamton, a spambot from an optional side quest, sells a powerful item called the Thorn Ring to Noelle. During the battle with Berdly, the player orders Noelle to use her new spell, Snowgrave. After initially resisting, she freezes
Development and release
The idea for Deltarune came to Toby Fox during a fever dream he had in 2011 while in college. In the dream, he saw the ending of a video game and decided to create it. Development of the game began in 2012, but was stopped before Fox created the first room. Many challenges, such as the game’s graphics, a new combat system, and Fox’s mental health, made Deltarune harder to create than Undertale. After releasing Chapter 4, Fox compared the size of each chapter to a full game, saying the first four chapters were like “two and a half Undertales.”
Deltarune is being made using GameMaker Studio 2. The game has a new battle system similar to the one in the Final Fantasy series, which is different from Undertale’s combat system (which was similar to games like Mother and Touhou Project).
Temmie Chang, who helped Fox with character art in Undertale, is the main artist for Deltarune. Fox designed Susie after playing Phoenix Wright: Ace Attorney. He originally based her on Maya Fey and wanted her to be “nice and cute.” However, as the character developed, she became more like a “thug.” Ralsei’s name came from Ralse, a character in an unfinished RPG Maker game made by Fox’s oldest brother when he was young.
To create one of the minibosses in Chapter 2, Fox asked artist Nelnal to design a “musical enemy,” which became Sweet Cap’n Cakes. At first, the artist made three characters, but Fox could not choose one, so he included all three in a single battle. Fox was unsure if players would like Spamton, as some testers found him scary. However, Spamton became popular, and merchandise featuring him sold quickly.
Fox originally planned to make a 3D model of Tenna himself. In 2016, he bought a Kinect to help animate the character using movements from MikuMikuDance. He wanted Tenna to look like “lineless 3D” inspired by Ghost Trick: Phantom Detective, but changed his mind after thinking it looked bad. The model was later created by Chelsea Saunders, who worked on Undertale promotional material, with help from Fox and others, including SmallBü. Fox worried players would not like Tenna, thinking he might be seen as a “budget Spamton.” However, he is happy players enjoy his character.
The game’s music was mostly composed by Toby Fox. It includes new themes for Deltarune and some from the Undertale soundtrack. The soundtrack is released in albums with each chapter, featuring guest musicians like Laura Shigihara, Lena Raine, Marcy Nabors, and Itoki Hana. Each album is published by Materia Collective.
After teasing something related to Undertale the day before, Fox released the first chapter of Deltarune for free on October 31, 2018. It was disguised as a “survey program” and described as a game for people who had finished Undertale. Originally, Fox planned to sell all chapters as a single package. Because he saw Deltarune as a larger project than Undertale, he said he needed a team to complete it. The first chapter was later released on Nintendo Switch and PlayStation 4 on February 28, 2019, after being announced in a Nintendo Direct. The console versions were developed and published by 8-4.
Development of the second chapter started in May 2020. Fox worked on the game’s story and characters and tested other game engines besides GameMaker Studio 2. He decided GameMaker was still the best choice and began working on Chapter 2 in May 2020 with Fox, Chang, and other team members. Fox said Chapter 2 is the largest chapter because of its many cutscenes and characters.
During a livestream celebrating Undertale’s sixth anniversary in September 2021, Fox announced Chapter 2 would be free on Windows and macOS on September 17, 2021. He said this was because the COVID-19 pandemic made life difficult for many people. The Switch and PS4 versions were updated to include Chapter 2 on September 23, 2021.
Initially, Chapters 3, 4, and 5 were planned to be released as a single paid game. By 2022, work on these chapters was happening at the same time. In September 2023, a playable version of Chapter 3 was completed. Because development took longer than expected, Fox said the first paid release would include only Chapters 3 and 4. He hired Robert Sephazon as a producer in early 2024, and his team set a deadline of September 1, 2024, to finish Chapter 4’s main content, which they met. Due to wrist injuries, Fox used speech-to-text software to type, with help from other team members for programming.
In late 2024, Fox said the next two chapters were being localized and ported to consoles for release in 2025. He also said work on Chapter 5 had started. During the April 2025 Nintendo Switch 2 Direct, it was announced that a paid version of Deltarune would release on June 5, 2025, as a launch title for the Switch 2. On May 9, Fox said the game would release on June 4, 2025, for PS4, Switch, PS5, and Windows in the West, and on June 5, 2025, in Japan.
The paid version includes Chapters 1–4, with future content planned as free updates. The game’s menu shows a total of seven chapters. The credits of Chapter 4 say the next chapter will release in 2026. On the tenth anniversary of Undertale in September 2025, Fox said he believed Chapter 5 would release in the second half of 2026. He also mentioned development of Chapter 6, saying at least one programmer had started working on “regular enemy bullet patterns.” In December 2025, Fox said progress was “excellent,” localization had begun, and it would take “several months to release the [chapter].”
Reception
The first chapter of Deltarune received many comparisons to Undertale. Jason Schreier of Kotaku and Dominic Tarason of Rock Paper Shotgun praised the chapter for improving parts of the game, with Tarason calling it "a higher-budget production." Mitchell Parton of Nintendo World Report thought the chapter did not change the game much but still had no problem with it. Mitch Vogel of Nintendo Life was less positive, saying that after how fresh Undertale was when it first came out, Deltarune felt "just more of the same."
Schreier said the chapter's "soundtrack should be enough of a selling point," and Adam Luhrs of RPGFan praised Fox's "clever use of musical themes," saying they fit well into the story. Both Parton and Tarason liked the pixel art, with Tarason calling it "more detailed and expressive" than Undertale. Michael Higham of GameSpot praised how the art "communicated so much with so little." However, Vogel criticized some areas for having "very little in the way of interesting design or presentation," calling the chapter "not a very pretty game to look at."
The gameplay was generally well received. Parton called it "unique," and Vogel said the combat was "an organic and well-implemented expansion of the original." However, Higham criticized some parts, like the "Card Castle" sequence, for being "a bit barebones." Allegra Frank of Polygon said the first chapter's sense of humor was one of its "defining features." Higham noted the game had "witty writing, snappy jokes, and absurdist humor," and Tarason praised the "fresh (and lovable) set of characters."
Screen Rant gave the second chapter a 4.5 out of 5, saying the quality "matches that of a full-price game" and made the wait for future chapters harder. It described the second chapter as feeling "more confident in its direction" and allowing players to "shape the fate of its characters." Ana Diaz of Polygon said the second chapter's world was "welcoming" despite being a "harsh challenge," praising its humor and noting it "complicates the moral and ethical questions" from Undertale while adding to the story started in Chapter 1.
The initial version of the paid release, which included Chapters 1–4, received positive reviews, with 100% of reviewers recommending it on OpenCritic. Brendan Graeber of IGN called Deltarune "something incredible" and said he would "not likely forget" it. Ana Diaz called it a "phenomenal expression" of Fox's creative style. Errielle Sudario of Checkpoint Gaming said the additional chapters were "worth the wait" and included "humor and heart" along with "more polish, challenges, and questions." Mitch Vogel of Nintendo Life said the game addressed his earlier criticism by creating a "distinct identity" that made it a "worthy follow-up to Undertale," though he still felt its unfinished nature left a "lingering feeling of dissatisfaction."
Shaun Cichaki of Vice said the combat design was "refined and elegant" compared to Undertale, and Alan Wen of GamesRadar+ praised the "delightful" creativity in the game's encounters. Sudario said some later combat required "time to master" but had a "payoff worth it." Vic Hood of TechRadar criticized some attacks on the Nintendo Switch 2 as "near impossible" to avoid, unlike the accuracy of a keyboard.
Many reviewers praised the art direction. Hood called it "stunning," and Wen said the pixel art was "crude but charming" with "richer use of sprites, color, and animations" than Undertale. Graeber said the game's music was an "embarrassment of phenomenal music," and Harold Goldberg of the New York Times called it "remarkably diverse." Vogel said the "deep and varied" soundtrack showed Fox was a "master of creating atmosphere." Sudario criticized some parts of the fourth chapter for being too dark to navigate, while Vogel still called the visuals "middling" and "a tad underwhelming," though he said the style worked well with the game's humor.
Reviewers also praised the game's plot and writing. Sudario said later chapters "expand meaningfully and emotionally" on the earlier story. Hood said the characters felt like "real friends," a feeling he had not experienced with a game before. Wen praised the characters for being "memorable, goofy, and flawed." Cichaki commended the game's "slapstick humor immediately pivoting into existential dread." Graeber said the plot had "hidden intrigue, beauty, and unpredictability," raising "unsettling questions" about the player-character relationship. Alisandra Reyes of Game8 praised the story's "deeper and more emotionally resonant" nature but criticized Chapter 3 for being "meandering" and a "detour" rather than a progression.
The game's soundtrack was nominated for the Game Audio Network Guild / MAGFest People's Choice Award at the 2019 G.A.N.G. Awards. At the 2025 Golden Joystick Awards, it was nominated for Best Indie Game – Self Published and Best Soundtrack. It won "Best Game" in the 2025 GameMaker Awards.
After the release of Deltarune's demo with Chapters 1 and 2, it had about 100,000 players on Steam at the same time, far more than Undertale's lifetime record. Deltarune was also one of the highest-grossing games on Steam in revenue when Chapters 3 and 4 were released. It was the best-selling digital game on the Switch 2 at the console's launch, beating Nintendo Switch 2 Welcome Tour and Mario Kart World.