Chunithm^[2] (stylized in all caps) is an arcade rhythm game developed and published by Sega. It was first seen in select Japanese arcades in November 2014, as part of a location test^[3][4] and was officially released on July 16, 2015 (2015-07-16).^[5] The game's title of Chunithm is a portmanteau of "chūnibyō" and "rhythm".^[4]

In Chunithm, players use touch and motion-based sensor bars to input commands that correspond to the notes scrolling down from the top of the screen. Depending on the type of note, players may be required to tap, hold, or slide their fingers against the bottom sensor bar or wave their hands up and down in the air between the sensors located on either side of the machine. The types of notes present in Chunithm are the following:

• TAP: The most common type of note, simply tap it when it reaches the judgement line. It is colored red.
• ExTAP: A gold colored variation of the TAP note, which will almost always grant the maximum judgement of "JUSTICE CRITICAL" when tapped, so long as you are not extremely early or late.
• HOLD: Visually, HOLD notes appear to be two TAP notes connected by a gold gradient, the player must tap and keep holding when the first note reaches the judgement line, and release as the tail end reaches the judgement line. The timing of the release is not important, but it is possible to let go too early, which would result in a MISS.
• SLIDE: SLIDE notes function almost identically to HOLD notes, with the exception that SLIDE notes can move left or right across the playfield. The player must move their hands in accordance with the direction it is moving; visually, they appear very similar to HOLD notes but colored blue.
• AIR: AIR is a modifier that can be added on top of the above-mentioned note types, visually presenting as a green arrow pointing up or a purple arrow pointing down. In the case of a green up arrow, the player must hit the regular note, and then lift their hand through the AIR sensing zone. Purple AIR arrows are typically found after an AIR-HOLD or AIR-ACTION section, as they require the player to quickly drop their hand down through the AIR sensing zone and onto the touch sensor.
• AIR-HOLD: A long green note that can be added onto an AIR note, requiring the player to keep their hand in the AIR sensing zone until the note ends.
• AIR-ACTION: Functioning as an AIR version of the TAP note, the player must wave their hand up or down in the AIR sensing zone with correct timing, mimicking a tap in the air.
• FLICK: Exclusive to the two highest difficulties, "MASTER" and "WORLD'S END", FLICKs function similarly to TAP notes, however instead of simply tapping, the player must quickly swipe their hand to the left or right as the note reaches the judgement line.
• DAMAGE: Exclusive to "WORLD'S END", DAMAGE notes function as the polar opposite to TAP notes. Tapping a DAMAGE note at any point will result in a MISS, and the player must simply not touch them in order to get a "JUSTICE CRITICAL".

CHUNITHM NEW introduces two new AIR note types:

• AIR-SLIDE: Due to the methodology with which the game detects AIR inputs, AIR-SLIDE notes are functionally identical to AIR-HOLDs; they can move left or right like SLIDE notes, however, this is simply for visual flair.
• AIR-CRUSH: Similarly, AIR-CRUSH notes are merely just a visually distinct version of AIR-ACTION, there can be many of them stacked on top of each other, while only requiring a single motion to be hit.

Since it's release, Chunithm has seen several expansions with new songs and gameplay additions, usually released biannualy. Songs are split into different categories: Pops and Anime, Niconico, Touhou Project, Variety, Worlds End, Gekimai, and Irodorimidori.

Chunithm NEW is the first major reboot of the series,^[6] introducing multiple gameplay improvements and adjustments. It was released on November 2021 alongside new "Gold Model" cabinets.^[7] "Silver Model" cabinets can be converted using conversion kits to run NEW and its future expansions.^[8]

Additions made to Chunithm NEW and the improved Gold Model cabinets include:

• The consolidation of character skills into 12 universal skills that can be upgraded with Skill Seeds
• Reorganization of the difficulty levels, with the maximum increased from 14 to 15
• 2 new note types, AIR-SLIDE and AIR-CRUSH
• National Matching, a new mode where players compete with others around the world in 4 songs
• Chuni Penguin, the game's mascot, now appears during songs in the bottom left corner, and can wear costumes won from National Matching
• A 120 frames per second monitor and improved sound and touch hardware
• Support for cashless payment systems

Chunithm features several scoring mechanics based on your performance of a song.

During gameplay, there is a gold meter at the top of the screen, this is your GAUGE. Below it is an indicator that tells you how many times you must fill it in order to CLEAR the song. You fill the GAUGE by hitting notes consecutively, missing a note will cause it to rapidly deplete.

After completing a song you are taken to a score screen where you are shown a variety of details, such as your grade, total judgement counts, and score, as well as a handful of other details if the player is playing on a registered online profile.

Your score, and thus your grade, is determined by calculating your overall accuracy using the below values, and then multiplying by 10000.

For example, if you were to play a song with 300 total notes and get 280 JUSTICE CRITICALS, 18 JUSTICES, 1 ATTACK, and 1 MISS, the formula for your accuracy rating would be

The table below lists all of the achievable grades as of LUMINOUS PLUS

Your score is also assigned a title, depending on a few different goals. The available titles are as follows:

In Chunithm, the rating system exists as a rough indicator of a player's skill level. Rating is calculated from the player's top 30 scores as well as their top 10 scores from the most recent 30 songs that they have played.

With the launch of CHUNITHM NEW, the rating system underwent a redesign, dividing it into nine levels based on color.

The first version of Chunithm released outside of Japan, "CHUNITHM SUPERSTAR", was released in November 2020. "CHUNITHM SUPERSTAR" is based on "CHUNITHM STAR" that was released back in 2017.^[9]

"CHUNITHM SUPERSTAR PLUS" was released on September 2, 2021 via an online update. This new version added the following to the game:

• Course Mode
• WORLD'S END

CHUNITHM NEW International Version was released in March 2022. Due to differences with the Japanese version, data will still be separated.

The launch dates, its countries/areas, and the version first released in these countries/areas are:

• Singapore: November 26, 2020 (CHUNITHM SUPERSTAR)
• Taiwan: November 27, 2020 (CHUNITHM SUPERSTAR)
• Hong Kong: December 2, 2020 (CHUNITHM SUPERSTAR)
• Macau: December 3, 2020 (CHUNITHM SUPERSTAR)
• Korea: December 9, 2020 (CHUNITHM SUPERSTAR)
• Australia: February 2, 2021 (CHUNITHM SUPERSTAR)
• New Zealand: March 27, 2021 (CHUNITHM SUPERSTAR)
• Thailand: April 3, 2021 (CHUNITHM SUPERSTAR)
• Mainland China: September 8, 2022 (CHUNITHM NEW)^[a]
• Malaysia: October 12, 2022 (CHUNITHM NEW PLUS)
• Philippines: October 31, 2022 (CHUNITHM NEW PLUS)
• Indonesia: September 16, 2023 (CHUNITHM SUN)

In addition, many Round1 locations in the United States feature CHUNITHM PARADISE LOST cabinets, but these cabinets are offline, and have a limited selection of songs.