Hatsune Miku: Colorful Stage!

Hatsune Miku: Colorful Stage! (subtitled Brand New World from its 3rd anniversary) is a rhythm game developed by Colorful Palette and published by Sega. The game is a spin-off from Sega's Hatsune Miku: Project DIVA series, and features 6 Virtual Singers of Crypton Future Media, Hatsune Miku, Megurine Luka, Kagamine Rin and Len, MEIKO, and KAITO, alongside the cast of 20 original human characters that are split into five themed units. Set in the real world where Virtual Singers only exist as fiction, the characters come across another dimension called "SEKAI," where various "true feelings" are projected.

The game was released for Android and iOS devices on September 30, 2020. Sega released an English server of the game worldwide on December 7, 2021, with expansion to 5 countries in Southeast Asia in September 25, 2023. A Taiwanese server, published by Ariel Network, was released on September 30, 2021. A Korean server was released on May 20, 2022 in South Korea, published by Nuverse.

Gameplay
Colorful Stage gameplay consists of tapping notes as they slide toward the bottom to the rhythm of a chosen song; players have to tap, slide and flick to match new free-form rhythm notes, and special yellow notes that are worth more points towards the score. The overall gameplay is similar to Sega's Persona Dancing (Atlus), Chunithm and Bandai Namco's The Idolmaster-themed rhythm games, the players are given 1,000 health points to clear a song with the ability to heal through character skills, and one can adjust song speed and difficulty to their liking. In lieu of an energy system that is prevalent in most free-to-play games, Hatsune Miku: Colorful Stage utilizes Live Boosts that increases rewards for completing a song, and players can continue playing even when they run out of boosts.

Players gain experience points (EXP) by clearing songs and listening to overworld conversations between characters. Such talks are fully voiced with 2.5D movement via Live2D technology, and their conversations are depicted in a visual novel-style presentation that is prepared for each group, including the Virtual Singers such as Miku. Further dialogues are added over time through events. EXP also improves a unit's rank, which unlocks additional chapters in group stories. Cards, which use a star ranking system to determine rarity (four stars being the rarest), are acquired via the gacha system, a luck-based mechanic in which players spend the in-game currency Crystals with the hope of winning their desired cards. Although Project SEKAI is a free-to-play game, players can spend real-life money to acquire in game currency.

The game also features Virtual Lives, a mode where players can go to a virtual concert, similar to augmented reality or a Vocaloid live concert, where players can interact with one another. They can see other players all around the world and their favorite group performing via 3D animation.

The game initially launched with 28 songs, with around four new songs added per month to the game; as of May 2024, a total of 429 songs are included. The tracklist mainly consists of Vocaloid songs or those from Vocaloid producers, with most songs having two versions: the original version (or new versions specifically made for the game; named "Virtual Singer version" in-game), and SEKAI versions, having the song covered by the original characters, and sometimes joined by a Virtual Singer. Some songs also have a 3D MV or animated MV, with animated MVs either being newly created for the game (named "2D MV" in-game) or original. Songs without an MV are played with a static 2D background, known as "Lite" in game.

Setting
Hatsune Miku: Colorful Stage is set in the real world, specifically in Shibuya, Tokyo. In this game, Hatsune Miku and her friends are famous fictional singers existing in the real world as Virtual Singers. They sing songs from creators all over the world, but they also exist in "SEKAI," (セカイ) a mysterious world different from the real world that is created from a person's "true feelings", featuring various visual appearances based on the person. There are as many SEKAI as there are emotions, and its form changes depending on the person's emotions. Therefore, the focus of the game is on the original characters and their journeys to find their "true feelings" with the help of the Virtual Singers.

In order to enter SEKAI, one must find and play the song "Untitled." This silent song has no melody or lyrics and is created at the same time as the SEKAI, and is mysteriously inserted on their devices. It can be anything, such as a game console, a smartphone, a smartwatch, a TV, a tablet, and a computer. When they play an "Untitled" song, they can travel between the real world and the SEKAI. As one is able to discover their true feelings, the song will contain a playable melody and lyrics, and well as its title.

Story
Each of the five groups and members has their own story, focusing on their journey to convey their "true feelings":


 * Leo/need: Ichika Hoshino wishes to recover her memories with her childhood friends Saki Tenma, Shiho Hinomori, and Honami Mochizuki to make them come together again, as their friendship had become strained in the aftermath of various circumstances that occurred during middle school. She entered the School SEKAI and met a punk-rock-styled Miku, who told her to convey her feelings to her friends and overcome their differences. Ichika and her friends eventually formed a band to restore their friendship and discover their shared memories through music.
 * MORE MORE JUMP!: Minori Hanasato has always dreamed of becoming an idol. Despite having failed auditions multiple times, she never gives up and hopes to pass an audition one day. She later entered the Stage SEKAI and met an idol-like Miku, who encouraged her to make her dream come true. She then formed an idol group with three former idols (Haruka Kiritani, Airi Momoi, and Shizuku Hinomori) who retired from their career due to problems with their agencies.
 * Vivid BAD SQUAD: Kohane Azusawa has been deeply passionate about street music ever since she stumbled upon a singing session by An Shiraishi. Captivated by her singing, Kohane joined An to become a street musician as well, and later teamed up with fellow musicians Akito Shinonome and Toya Aoyagi. She entered the Street SEKAI and met a hip-hop-styled Miku, and together they began the quest to surpass a legend.
 * Wonderlands x Showtime: Tsukasa Tenma has always wanted to make his sickly sister, Saki, happy, but as time passed, he couldn't remember why he wanted to be a star in the first place. He was hired to work part-time at the theme park Phoenix Wonderland, but the once-popular theater Wonder Stage he is assigned to has been deserted, unable to attract any visitors for years. There, he met Emu Otori, who desires to restore the theater to its former glory. Joined by Nene Kusanagi and Rui Kamishiro, they formed a musical theater troupe as they entered the Wonderland SEKAI and met a clown-like Miku, hoping to revive the theater's glory and make people happy.
 * Nightcord at 25:00: Kanade Yoisaki has been homeschooled and becomes reclusive because of a trauma she sustained as a result of an incident in the past. She formed an underground music circle with her three online acquaintances Mafuyu Asahina, Ena Shinonome, and Mizuki Akiyama, communicating over a voice-chat platform named "Nightcord" and meeting at 25:00 (1AM). None of them knew each other's true names or identities, only knowing each other by online aliases and through voice chat. Kanade was pulled into the Empty SEKAI by Miku, who urged her to help save Mafuyu, the group's lyricist who had mysteriously disappeared a week prior.

Characters
The characters are divided into five groups of four, each with a theme related to the groups' backstory, complete with Hatsune Miku in a thematic design to sing alongside them, and start with one other Virtual Singer (with the exception of Vivid BAD SQUAD, who have Len and MEIKO, and Nightcord at 25:00, who only have Miku herself). As the game's story progresses, new versions of each Virtual Singer appear in the different SEKAI.

Leo/need
An all-girl pop-rock band formed by a group of childhood friends who have learned to overcome their differences. Their SEKAI, the School SEKAI, consists of a classroom bathed in the afterglow of the sunset. They are initially supported by Hatsune Miku and Megurine Luka, who take on the form of band musicians. Their image color is Midnight Blue, and they represent memories.


 * Ichika Hoshino (星乃 一歌)
 * The leader of Leo/need, Ichika is the vocalist and guitarist of the band. Her name comes from how her parents met each other, "an encounter made because of one certain song". While appearing cool and stoic on the outside, she is actually a worrywart, especially when it comes to her childhood friends. She currently attends Miyamasuzaka Girls Academy in class 1-C and is the class president. A big fan of Hatsune Miku, Ichika was the first among her friends to discover the track "Untitled", which she found on her phone. Ichika also appears in the game's promotional art more often than the other original characters, as one of the main protagonists alongside Miku.
 * The leader of Leo/need, Ichika is the vocalist and guitarist of the band. Her name comes from how her parents met each other, "an encounter made because of one certain song". While appearing cool and stoic on the outside, she is actually a worrywart, especially when it comes to her childhood friends. She currently attends Miyamasuzaka Girls Academy in class 1-C and is the class president. A big fan of Hatsune Miku, Ichika was the first among her friends to discover the track "Untitled", which she found on her phone. Ichika also appears in the game's promotional art more often than the other original characters, as one of the main protagonists alongside Miku.


 * Saki Tenma (天馬 咲希)
 * Saki is the keyboardist of the band. She was hospitalized during her elementary and middle school days and was discharged during the first year of high school, only to find out that her childhood friends had grown apart. Along with Ichika, the two attempt to reunite the remaining two by forming a band, just like during their elementary school days. She suffers from an unspecified chronic disease that has caused her frequent hospitalizations. Saki aims to make the most of her time with her friends and make up for all the time she spent in the hospital. She has an older brother named Tsukasa, who is very protective of her and has been looking after her ever since she fell ill.
 * Saki is the keyboardist of the band. She was hospitalized during her elementary and middle school days and was discharged during the first year of high school, only to find out that her childhood friends had grown apart. Along with Ichika, the two attempt to reunite the remaining two by forming a band, just like during their elementary school days. She suffers from an unspecified chronic disease that has caused her frequent hospitalizations. Saki aims to make the most of her time with her friends and make up for all the time she spent in the hospital. She has an older brother named Tsukasa, who is very protective of her and has been looking after her ever since she fell ill.


 * Honami Mochizuki (望月 穂波)
 * Honami is the drummer of the band, and acts as the motherly figure of the group. During middle school, she was afraid of being isolated by her classmates, who accused her of being "two-faced" for siding with everyone. She decided to distance herself from her childhood friends and hang out more with her classmates instead. She later realized she had been running away from them in order protect herself.
 * Honami is the drummer of the band, and acts as the motherly figure of the group. During middle school, she was afraid of being isolated by her classmates, who accused her of being "two-faced" for siding with everyone. She decided to distance herself from her childhood friends and hang out more with her classmates instead. She later realized she had been running away from them in order protect herself.


 * Shiho Hinomori (日野森 志歩)
 * Shiho is the bassist of the band. She also works part-time at a live house and sometimes fill-in a bassist position. At the beginning of the unit's main story, she distanced herself from others so her friends would never get caught in the bad rumors about her. However, Shiho actually wanted to be reunited with her friends again. She has an older sister named Shizuku, whose affectionate nature towards her often irritates Shiho.
 * Shiho is the bassist of the band. She also works part-time at a live house and sometimes fill-in a bassist position. At the beginning of the unit's main story, she distanced herself from others so her friends would never get caught in the bad rumors about her. However, Shiho actually wanted to be reunited with her friends again. She has an older sister named Shizuku, whose affectionate nature towards her often irritates Shiho.

MORE MORE JUMP!
A pop idol group formed by one girl who dreams of becoming an idol and three girls who have quit being idols. Their SEKAI, the Stage SEKAI, consists of a concert stage illuminated by countless glow sticks. They are initially supported by Hatsune Miku and Kagamine Rin, who take on the form of idols. Their image color is Bright Green, and they represent hope.


 * Minori Hanasato (花里 みのり)
 * The leader of MORE MORE JUMP!, Minori is a clumsy yet easy-going first year high school student. Even though she is often hit by bad luck, she never gives up and continues to work hard with a single-minded heart. Minori is a big fan of the now-disbanded idol group "ASRUN", and idolizes Haruka Kiritani in particular. She hopes to become an idol herself, despite having failed every audition she has taken.
 * The leader of MORE MORE JUMP!, Minori is a clumsy yet easy-going first year high school student. Even though she is often hit by bad luck, she never gives up and continues to work hard with a single-minded heart. Minori is a big fan of the now-disbanded idol group "ASRUN", and idolizes Haruka Kiritani in particular. She hopes to become an idol herself, despite having failed every audition she has taken.


 * Haruka Kiritani (桐谷 遥)
 * A very popular idol who was once a member of the nationally famous idol group "ASRUN". The group suddenly disbanded, forcing Haruka to retire from the entertainment industry. Her hobby includes collecting penguin-related merchandise. She is the childhood friend of An Shiraishi, with whom she has had a friendly-rivalry relationship.
 * A very popular idol who was once a member of the nationally famous idol group "ASRUN". The group suddenly disbanded, forcing Haruka to retire from the entertainment industry. Her hobby includes collecting penguin-related merchandise. She is the childhood friend of An Shiraishi, with whom she has had a friendly-rivalry relationship.


 * Airi Momoi (桃井 愛莉)
 * A retired idol who used to appear often in a variety show as the persona "Happy Everyday". She is the middle child of her family and lives with her stay-at-home dad and two sisters, and has a close friendship with Nightcord member Ena. Her hobbies include idol research and shopping. She acts as the straight man of the unit.
 * A retired idol who used to appear often in a variety show as the persona "Happy Everyday". She is the middle child of her family and lives with her stay-at-home dad and two sisters, and has a close friendship with Nightcord member Ena. Her hobbies include idol research and shopping. She acts as the straight man of the unit.


 * Shizuku Hinomori (日野森 雫)
 * An elegant but airheaded high school sophomore. Formerly of the group "Cheerful*Days", she drew jealousy from her fellow idol unit members due to perceived favoritism. Unable to see any worth in continuing it, she quit her idol career. She holds a strong attachment to her younger sister Shiho, often to her annoyance.
 * An elegant but airheaded high school sophomore. Formerly of the group "Cheerful*Days", she drew jealousy from her fellow idol unit members due to perceived favoritism. Unable to see any worth in continuing it, she quit her idol career. She holds a strong attachment to her younger sister Shiho, often to her annoyance.

Vivid BAD SQUAD
A top-level hip-hop, teen pop, electronic and street music group formed to surpass a legend. They were originally two separate musical duos before their merger: Vivids and Bad Dogs. Their SEKAI, the Street SEKAI, consists of an alleyway with walls covered in graffiti and concert posters. They are initially supported by Hatsune Miku, who takes on the form of a street dancer, alongside MEIKO, who takes on the form of a café waitress, and Kagamine Len, who takes on the form of a disc jockey. Their image color is Vivid Red, and they represent passion.


 * Kohane Azusawa (小豆沢 こはね)
 * The leader of Vivid BAD SQUAD, Kohane is a shy first year girl who lacks self-confidence. She became interested in music after watching An perform at a live music café. The two later formed the unit "Vivids" to perform at different events. Kohane also enjoys photography and usually looks after her father's pet snake, Count Pearl.
 * The leader of Vivid BAD SQUAD, Kohane is a shy first year girl who lacks self-confidence. She became interested in music after watching An perform at a live music café. The two later formed the unit "Vivids" to perform at different events. Kohane also enjoys photography and usually looks after her father's pet snake, Count Pearl.


 * An Shiraishi (白石 杏)
 * An is the outgoing and lively daughter of Ken, one of the artists headlining the "RAD WEEKEND" event. She used to sing solo at events and on the street, until she met Kohane and asked her to be her singing partner. She can get hotheaded at times, but is generally very cheerful. An is a first-year student at Kamiyama High School, where she works as a hall monitor. She is also childhood friends with Haruka Kiritani.
 * An is the outgoing and lively daughter of Ken, one of the artists headlining the "RAD WEEKEND" event. She used to sing solo at events and on the street, until she met Kohane and asked her to be her singing partner. She can get hotheaded at times, but is generally very cheerful. An is a first-year student at Kamiyama High School, where she works as a hall monitor. She is also childhood friends with Haruka Kiritani.


 * Akito Shinonome (東雲 彰人)
 * , Reina Aoyama (child)
 * Akito usually appears to be a well mannered boy, but underneath is his brash and rough side, unafraid to say what's on his mind. He was inspired to get into music by An's father Ken and aspires to surpass his "RAD WEEKEND" event one day. Akito formed the group "BAD DOGS" with Toya, which then combined with An and Kohane's "Vivids". He has an older sister named Ena, with whom he has a rocky relationship.


 * Toya Aoyagi (青柳 冬弥)
 * Toya is the reserved youngest son of a famous classical musician, who had him learn classical music from a very young age. Against his father's wishes, Toya formed the street music group "BAD DOGS" alongside Akito. Toya looks up to Tsukasa Tenma, whom he's known from a young age and respects, because Tsukasa gave him the courage to give up classical music. He is very good at claw machine games, and usually gives his prizes to Akito or Tsukasa as a gift for their sisters.
 * Toya is the reserved youngest son of a famous classical musician, who had him learn classical music from a very young age. Against his father's wishes, Toya formed the street music group "BAD DOGS" alongside Akito. Toya looks up to Tsukasa Tenma, whom he's known from a young age and respects, because Tsukasa gave him the courage to give up classical music. He is very good at claw machine games, and usually gives his prizes to Akito or Tsukasa as a gift for their sisters.

Wonderlands x Showtime
Wonderlands x Showtime (ワンダーランズ×ショウタイム) is an eccentric musical theater troupe formed to "put a smile on people's faces to make the world happy". Their SEKAI, the Wonderland SEKAI, consists of an amusement park filled with fantastical encounters like singing flowers and walking stuffed animals. They are supported by Hatsune Miku, who takes on the form of a cat-like troupe jester, and KAITO, who takes on the form of a suited troupe actor. Their image color is Pop Yellow, and they represent happiness.


 * Tsukasa Tenma (天馬 司)
 * The troupe leader of Wonderlands x Showtime, Tsukasa is a self-absorbed and enthusiastic high school sophomore who aims to be a star to make people smile. He is working part-time at theme park Phoenix Wonderland's Wonder Stage and aims to become the world's future star. He has a positive relationship with his younger sister, Saki, who was the catalyst for his goal of becoming a star that makes people smile.
 * The troupe leader of Wonderlands x Showtime, Tsukasa is a self-absorbed and enthusiastic high school sophomore who aims to be a star to make people smile. He is working part-time at theme park Phoenix Wonderland's Wonder Stage and aims to become the world's future star. He has a positive relationship with his younger sister, Saki, who was the catalyst for his goal of becoming a star that makes people smile.


 * Emu Otori (鳳 えむ)
 * Emu is a cheerful and free-spirited girl, her family has the ownership of Phoenix Wonderland. She has been determined to keep the theme park's Wonder Stage theater running, so as to preserve her late grandfather's legacy. Her catchphrase is "Wonderhoy!" (わんだほーい). She is the youngest daughter in her family, and has an older sister and two older brothers. Outside of Wonderlands x Showtime, Emu is classmates with Honami and is acquainted with Mafuyu Asahina, whose smile frightens her.
 * Emu is a cheerful and free-spirited girl, her family has the ownership of Phoenix Wonderland. She has been determined to keep the theme park's Wonder Stage theater running, so as to preserve her late grandfather's legacy. Her catchphrase is "Wonderhoy!" (わんだほーい). She is the youngest daughter in her family, and has an older sister and two older brothers. Outside of Wonderlands x Showtime, Emu is classmates with Honami and is acquainted with Mafuyu Asahina, whose smile frightens her.


 * Nene Kusanagi (草薙 寧々)
 * Nene is a shy and introverted girl who is experienced in stage performances, but suffers with stage fright, leaving her unable to sing during a stage performance. Despite her shy personality, she can be very blunt and sharp-tongued, especially towards her group members. She enjoys video games and is highly skilled at them. Nene ends up becoming friends with Ichika due to their similar personalities.
 * Nene is a shy and introverted girl who is experienced in stage performances, but suffers with stage fright, leaving her unable to sing during a stage performance. Despite her shy personality, she can be very blunt and sharp-tongued, especially towards her group members. She enjoys video games and is highly skilled at them. Nene ends up becoming friends with Ichika due to their similar personalities.


 * Rui Kamishiro (神代 類)
 * Rui is Nene's childhood friend who has an interest in directing. He is considered a genius. His hobbies include creating robots and other inventions to use in shows. One of his notable creations is RoboNene, a Mikudayo-lookalike robot with an appearance similar to Nene, made specifically to assist her in stage performances. During middle school, Rui was a social outcast, and many others looked down at him due to his unusual and potentially dangerous ideas, although he did manage to befriend fellow outcast Mizuki.
 * Rui is Nene's childhood friend who has an interest in directing. He is considered a genius. His hobbies include creating robots and other inventions to use in shows. One of his notable creations is RoboNene, a Mikudayo-lookalike robot with an appearance similar to Nene, made specifically to assist her in stage performances. During middle school, Rui was a social outcast, and many others looked down at him due to his unusual and potentially dangerous ideas, although he did manage to befriend fellow outcast Mizuki.

Nightcord at 25:00
Nightcord at 25:00 (25時、ナイトコードで.) is an indie underground music circle whose identities are shrouded in mystery. Each of the group's members have expressed thoughts of "wanting to disappear". Their SEKAI, the Empty SEKAI consists of an empty space with nothing in it except for a few dim rays of light and distorted screens. The only singer to accompany them at game launch is Hatsune Miku, who is mysterious in her personality as well as a gothic lolita appearance, though this changes later on. Their image color is Dark Purple, and they represent trauma. Nightcord refers to the online voice-chat platform the group use, similar to the real-life chat platform Discord.


 * Kanade Yoisaki (宵崎 奏)
 * The leader of Nightcord at 25:00, the composer of the circle who goes by the internet name "K". Kanade is a hikikomori who always wears a jersey and attends online school. Her father was also a music composer, who fell ill of an occupational stress and was hospitalized due to the sense of being compared to his daughter. This event traumatized Kanade and led her to vow to "make songs that can save people".
 * The leader of Nightcord at 25:00, the composer of the circle who goes by the internet name "K". Kanade is a hikikomori who always wears a jersey and attends online school. Her father was also a music composer, who fell ill of an occupational stress and was hospitalized due to the sense of being compared to his daughter. This event traumatized Kanade and led her to vow to "make songs that can save people".


 * Mafuyu Asahina (朝比奈 まふゆ)
 * The lyricist of the circle, known by the internet name "Yuki". Pressed into fulfilling the expectations of others, especially her mother, Mafuyu lost sight of herself and her emotions. She puts up a "good girl" facade around other people, but reverts to her real, somber self in front of her group members. Outside the circle members, only Emu Otori seems to be aware of this.
 * The lyricist of the circle, known by the internet name "Yuki". Pressed into fulfilling the expectations of others, especially her mother, Mafuyu lost sight of herself and her emotions. She puts up a "good girl" facade around other people, but reverts to her real, somber self in front of her group members. Outside the circle members, only Emu Otori seems to be aware of this.


 * Ena Shinonome (東雲 絵名)
 * The artist of the circle going by the internet name "Enanan", Ena is the one behind the illustrations for the circle's music video. She likes to post her selfies to social media to gain likes, but actually suffers from an inferiority complex. Believing she has no talent in painting, she is so pessimistic that she always thinks people would come to make fun of her artwork. She is a strong-willed girl, especially towards Mafuyu, but is still generally nice and cares for others. Ena is Akito's older sister, and they have a tough relationship. In contrast, she maintains a cordial friendship with Airi Momoi.
 * The artist of the circle going by the internet name "Enanan", Ena is the one behind the illustrations for the circle's music video. She likes to post her selfies to social media to gain likes, but actually suffers from an inferiority complex. Believing she has no talent in painting, she is so pessimistic that she always thinks people would come to make fun of her artwork. She is a strong-willed girl, especially towards Mafuyu, but is still generally nice and cares for others. Ena is Akito's older sister, and they have a tough relationship. In contrast, she maintains a cordial friendship with Airi Momoi.


 * Mizuki Akiyama (暁山 瑞希)
 * Mizuki is the video editor of the circle's music videos, known by the internet name "Amia". They are playful and enjoy teasing their group members, particularly Ena. Despite their cheerful personality, Mizuki is said to have a "secret" deliberately left unknown to fellow circle members as well as the audience. Mizuki enjoys designing clothes in their free time and has an obsession with anything cute. For unexplained reasons, Mizuki's gender is currently listed as "unknown" in official sources. They are considered an outcast by other people in their school and were depicted with shorter hair and a boys' school uniform in flashbacks of when they were in middle school. Mizuki later became friends with Rui Kamishiro, another outcast. Although Mizuki and Rui drifted when they both started getting involved with their own groups, they are still on talking terms and have remained in friendly nature when interacting with one another.
 * Mizuki is the video editor of the circle's music videos, known by the internet name "Amia". They are playful and enjoy teasing their group members, particularly Ena. Despite their cheerful personality, Mizuki is said to have a "secret" deliberately left unknown to fellow circle members as well as the audience. Mizuki enjoys designing clothes in their free time and has an obsession with anything cute. For unexplained reasons, Mizuki's gender is currently listed as "unknown" in official sources. They are considered an outcast by other people in their school and were depicted with shorter hair and a boys' school uniform in flashbacks of when they were in middle school. Mizuki later became friends with Rui Kamishiro, another outcast. Although Mizuki and Rui drifted when they both started getting involved with their own groups, they are still on talking terms and have remained in friendly nature when interacting with one another.

Development
The game was first announced on August 30, 2019, at Magical Mirai 2019. The development is done by the Colorful Palette, a newly established subsidiary of CyberAgent's Craft Egg (developers of rhythm game BanG Dream! Girls Band Party). Yuichiro Kondo, the first producer of Girls Band Party, also serves as the producer for this game. The project started in 2017 and was initially being developed entirely by Craft Egg, but Kondo thought it was necessary to avoid a situation where the project would clash with the development of Girls Band Party, so he created Colorful Palette with Craft Egg's core members within the company. It was developed with Unity, and uses Crypton's Piapro Studio NT engine for speech synthesis.

The title is a rhythm game that features arrangements of songs made by various artists over the years using the Vocaloid software. The original story of the game is told in a visual novel and musical film-style. The direction of the game's design and concept is different from other Hatsune Miku-related games, such as Sega's Hatsune Miku: Project DIVA, where the player and Hatsune Miku face each other directly and communicate in the game. The project is said to be "a work that embodies the existence of Hatsune Miku" and explores the relationship between music and people. One of the reasons behind this format was the idea of "wanting the younger generation to listen to more Vocaloid music and other songs from the internet." Therefore, while knowing that there could be people opposed to the idea of addition of original characters, it was decided to develop such a setting.

Release
The game's pre-registration was originally set to begin in late April, but was delayed until further notice due to the COVID-19 pandemic. The pre-registration later started on July 17, 2020, and Sega revealed the goals were set from 100,000 to 1,000,000 pre-registrations. In September 2020, the pre-registrations later reached 1,000,000 and players who pre registered received rewards.

The game's worldwide release was announced in August 2021 with a slightly different title, Hatsune Miku: Colorful Stage!. Nuverse released the game for the Hong Kong, Macau, and Taiwan markets on September 30, 2021. Nuverse is also managing the release in Mainland China, South Korea, and Southeast Asia, with a release date to be announced. Sega released the game for all other regions (especially Western world including Oceania, Europe and North America) on December 7, 2021. The game was released on 25 September 2023 for Southeast Asia, said to be an extension for the global server.

Reception
, Project SEKAI has reached over 5 million users and received positive reviews. The game was ranked 9th on Twitter's Most Talked About Video Games list in 2021.

Anime series
A mini anime series titled Petit SEKAI (ぷちセカ) was announced during the game's first anniversary live stream. The anime mini-series has 10 episodes that will be broadcast through Tokyo MX and is available for free to watch through the game's official YouTube channel. The anime has the characters drawn in chibi-style, and a bit of gag-esque story that is slightly different from the original story. It premiered on January 13, 2022. Official English subtitles are made available sometime after the official premiere.

Journey to Bloom
Another short animated series was announced during the 3rd anniversary Wondershow Channel Livestream called "Journey to Bloom," which is the summary of each units' main story. The series is available for free to watch through the game's official YouTube channel. Official English subtitles are made available sometime after the official premiere. The series is produced by P.A. Works.

Printed media
An anthology comic was released on November 25, 2021, by Ichijinsha's DNA Media Comics. The manga collection are drawn by 15 different artists with their own depiction of the game, hence its content may not count as canon. An official visual fan book was released on November 26, 2021.

Concerts
The game has held two types of live concerts: SEKAI Symphony and Colorful Live.

SEKAI Symphony (セカイシンフォニー) is an annual orchestra concert for the songs that has been featured in the game. It is held annually held at Pacifico Yokohama and is performed by SEKAI Symphony Special Band of Tokyo Philharmonic Orchestra. The first concert, held on October 16, 2021 featured Tsukasa Tenma and Nene Kusanagi's voice actors Daisuke Hirose and Machico as guests. The second concert was held on June 11, 2022, featuring the voice actresses of Nightcord at 25:00 (Tomoki Kusunoki, Rui Tanabe, Minori Suzuki, and Hinata Sato) as guests. The third concert was held on June 10, 2023, featuring Ichika Hoshino and Saki Tenma's voice actresses Ruriko Noguchi and Karin Isobe as guests. The fourth concert will be held on June 8, 2024, featuring the voice actors of Vivid BAD SQUAD (Akina, Tomomi Jiena Sumi, Fumiya Imai, and Kent Itō) as guests.

Colorful Live is a live concert featuring characters from the game in hologram, 3D model that is different from the one seen in the game. It follows the nature of Magical Mirai, an annual Miku-centered live concert, where all of the 26 characters (20 original characters + 6 Virtual Singers) will sing and dance along with real life band performers. The first concert, titled Colorful Live 1st -Link- was held on January 28–30, 2022 at Makuhari Messe. There was also paid live stream held on Abema TV.

Anniversary event
An annual event called Project Sekai Thanks Festival is being held on late September to celebrate the game's upcoming anniversary (September 30). Many of the original characters' voice actors and actress make appearance in the event, who will then perform in a mini concert and reading act. Some will perform as the host in the special edition of Sekai Broadcast Livestream, a talk show, as well Sekai Radio. An exhibition is also set up inside the venue. The event was first held on to celebrate the game’s upcoming second anniversary, which was held on September 23-24, 2022 at Tachikawa Stage Garden. The second event was held at Tokyo Dome City Hall on September 16-17, 2023. The third event will be held on September 26-27, 2024 at Yokohama Buntai.