Osu!

Osu! (stylized as osu!) is a free-to-play rhythm game originally created and self-published by Australian developer Dean Herbert. Inspired by gameplay of the Osu! Tatakae! Ouendan series, it was released for Microsoft Windows on 16 September 2007, with later ports to macOS, Linux, Android and iOS.

Osu!'s gameplay, based on the Osu! Tatakae! Ouendan series of rhythm games, primarily involves clicking notes, which appear as circles, using the mouse cursor. Since the game's release, three other game modes have been added, taking inspiration from Taiko no Tatsujin and Beatmania. Unlike many rhythm games, levels in Osu! are created and uploaded by users, increasing the range and volume of the song library, which is a factor contributing to the game's popularity.

The game has a significant connection to Japanese culture and anime music. It has also had effects on the esports industry—professional gamers use Osu! to warm up and practice, and the community frequently organizes tournaments between players.

Gameplay
Osu! is a rhythm game in which hit circles appear as notes over a song's runtime, and the objective is to click on the circles at the appropriate time and in the correct order,  aided by rings called approach circles that close in on the hit circles to visually indicate the timing. The core gameplay is inspired by the Nintendo DS rhythm game Osu! Tatakae! Ouendan and its sequel ''Elite Beat Agents. '' Other types of notes require that the player click and hold while moving the cursor. If the player misses too many circles, they fail the song and must retry. In-game settings, called mods, can change gameplay in different ways—for example, by speeding up the song or decreasing the size of circles. Songs are mapped to levels called beatmaps, and the same song can have multiple beatmaps of varying difficulties. Some beatmaps, including a tutorial, are bundled with a new installation of the game, but more can be downloaded from the game's website.

Beatmaps can be created and uploaded by all users. In the game's single-player mode, scores on beatmaps can be compared with other players, who are ranked on an online leaderboard. Scores are primarily measured using their performance points, which account for various aspects of a player's skill. Users can add others as friends and chat in-game, and the multiplayer mode allows groups of people to play beatmaps synchronously with each other.

Game modes
The game's original and most popular mode, based on Ouendan, is also known as osu!standard. There are also three alternative game modes, osu!mania, osu!taiko, and osu!catch. In osu!mania, a mode based on rhythm game series such as Beatmania and Guitar Hero, the player must press the correct keys on the keyboard when notes reach the bottom of the screen. osu!taiko is based on Taiko no Tatsujin; it involves circles moving from right to left, requiring keypresses when they reach the left side. osu!catch is based on EZ2Catch, a game mode in EZ2DJ. In it, fruits fall from the top of the screen and the player controls a character at the bottom whom they can move left and right with the goal of catching as much fruit as possible.

Development
Osu! was created by Dean Herbert, an Australian developer known online as "peppy", as a computer version of ''Osu! Tatakae! Ouendan and Elite Beat Agents.'' One of his goals was to create longevity through enabling users to generate beatmaps. Herbert had experience creating video games prior to Osu!, having made some during high school and university, but has said he did not think it would become his job. He began developing Osu! while attending university and had a working build of the game after a few hours, which he shared with friends. It was written in C using the XNA framework. The game's first public release was on 16 September 2007, and an open beta was officially available starting on 17 October. Due to the game's growth in popularity as well as user feedback, Herbert later added the extra game modes osu!mania, osu!taiko, and osu!catch. After releasing Osu!, Herbert, who had been working full-time for an IT company, gradually reduced his work hours to focus on maintaining Osu!. According to Herbert, as of a July 2014 interview for the official Osu! YouTube channel, the user interface of the game client and official website were undergoing full "revamps". In the same interview, he expressed interest or intentions to add major features to the game, such as a multiplayer power-up system inspired by Ouendan and TetriNET, 3D rotation of the field of play,  and expanded multiplayer lobbies.

Community and popularity
Osu! has continued to gain popularity since its release, being widely shared on video and live streaming platforms like YouTube and TikTok. The game works on a model of community-generated beatmaps, which has been cited as a significant factor in its popularity and longevity. A large portion of the available music consists of songs from anime —the game itself is aimed at foreign fans of Japanese culture and is influenced by it, particularly due to its inspiration from Ouendan and the general continuing association of rhythm games with Japan since the 1990s.

Tournaments are held frequently as another mode of competition. The Osu! World Cup is an annual tournament which comprises a group stage and bracket of the 32 highest-seeded national teams in the world, usually with 6 to 8 players on each team.

Due to the game's emphasis on quickly moving the mouse cursor to precise points on the screen, some players of multiplayer online battle arena games and first-person shooter games use it to improve reflexes and mouse control, and it has been specifically recommended by some esports professionals like Ninja and EFFECT.

Devices
Osu! has been noted for encouraging the use of unique input devices—although the game can be played with a computer mouse, it is often recommended to use a graphics tablet with a pen, which more closely emulates the gameplay of Ouendan. The accessibility of using a mouse and keyboard is another reason given for the game's popularity. Gaming keyboard manufacturer Wooting announced in March 2023 a three-key keyboard dedicated to playing Osu! due to the popularity of their keyboards among the game's players.

Critical reception
Jeuxvideo.com reviewed Osu! favorably with 18/20 points in 2015, praising its simple gameplay and its expansive community, but complaining about a high skill floor and its unoriginal gamemodes, as well as the prevalence of Japanese music, which they felt was excessive. In 2010, MMOGames.com reviewer Daniel Ball said that while the game was very similar to Elite Beat Agents, it was differentiated by its community's large library of high-quality community made content and customization.