Osu!

osu! is a rhythm game with multiple distinct game modes.[1:38] If the player misses too many notes, 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 increasing the size of circles. Songs are mapped to levels called beatmaps, and the same song can include 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 or directly from the game.

Beatmaps can be created and uploaded by all users, though only certain beatmaps are considered to be official game content, known as ranked maps. In order for a beatmap to become ranked, it must go through a specific ranking process. 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 also measured using their performance points (abbreviated as pp), which account for various aspects of a player's skill and determines the player's rank on the overall player ranking. Users can add others as friends and chat in-game, and multiple multiplayer modes allow groups of people to play beatmaps either synchronously or asynchronously with each other.[0:58]

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 craft their own beatmaps. , 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.

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 similar to Elite Beat Agents, it was differentiated by its community's large library of high-quality community-made content and customization.

osu! has continued to gain popularity since its release, being widely shared on video and live streaming platforms like YouTube and TikTok. An artificial intelligence VTuber called Neuro-sama beat the top-ranked osu! player in 2022, mrekk, in a one-versus-one battle.