osu!

osu!
Developer(s)	Dean "peppy" Herbert
Platform(s)	Microsoft Windows Android (starting 2.1) OS X iOS (App Store) Cydia Windows Phone
Release date(s)	September 16, 2007
Genre(s)	Music (Beat)
Mode(s)	Singleplayer, Multiplayer

osu! is a freeware rhythm game developed by Dean "peppy" Herbert, originally for Microsoft Windows. It is written in C# on the .NET Framework. The game has also been ported to OS X, iOS, Android, and Windows Phone.^[1] Its gameplay is based on commercial titles including Osu! Tatakae! Ouendan, Elite Beat Agents, Taiko no Tatsujin, beatmania IIDX, O2Jam, and DJMax.

Gameplay

Game levels are called beatmaps. In each beatmap, a song will play and different Beats hit elements (hit circles, sliders and spinners) will appear on the play field. Players must use a pointing device to manipulate these elements in time with the playing song's rhythm in order to earn points. The use of a graphics tablet in combination with a keyboard is common in osu!, although some players do use a mouse.

Difficulties

There are five default difficulties which are defined through the game as Easy, Normal, Hard, Insane, and Expert (commonly known as Another or Extra). Beyond this, "Marathon" difficulty is reserved for beatmaps which are longer than 10 minutes long. "TAG" difficulties are another popular variation to the standard difficulties, intended to be played by multiple people taking turns at set intervals in the beatmap. Content creators may choose to name their difficulties to anything outside of the standard naming conventions.

Objective

The main objective when playing osu! is to hit, complete, and clear enough hit circles, sliders, and spinners to keep the health bar, which drains at a steady rate throughout the game, above 0 until the beatmap is over. More experienced players will often strive for a more specific and difficult goal, like improving their high score or grade on a particular beatmap, usually by attempting to time their hits better and avoid as many misses as possible to increase combo multipliers.

Hit circles

Also sometimes referred to as notes, hit circles are a common object on nearly every beatmap. When a hit circle appears, a ring, called the approach circle, will appear around it and begin to shrink. In order to score points from a hit circle, players must place their cursor over the circle and click the hit button as the approach circle touches the edge of the hit circle.

Sliders

Sliders appear as two hit circles with a solid path, called a slider track, between them. As with hit circles, an approach circle appears at the beginning of a slider track, which must be clicked when the approach circle touches its edge. Unlike hit circles, however, after the start of a slider has been hit, a ball, called the slider ball, will begin to roll along the slider track, and players must continue to hold down the hit button and keep their cursor hovered over or near the slider ball until it has reached the end of the slider. Sometimes a slider end will have an arrow, called the reverse arrow, which means the player will be required to follow the slider ball back to its starting point.

Spinners

A spinner is a large circle that takes up most of the play field when it appears. A ring like the approach circle of hit circles and sliders will also appear and begin to close on the spinner's center. Players must hold down the hit button and spin their cursor around the center of the spinner. As players continue to spin, the spinner gauge at either side of the screen begins to fill, and once it has been filled, the player will be notified that the spinner has been cleared. Continued spins after this and until the ring reaches the spinner's center will award bonus points.

In the new version the approach circle is replaced by the changing of the color of the border of the spinner that gradually fades to red as the spinner approaches the end. The gauge is also absent.

Hits and misses

Hit circles, sliders, and spinners have different criteria to how they can be hit or missed, and to how points can be gained.

Clicking the hit button at the right time while the cursor is hovered over a hit circle or the start of a slider, or clearing a slider will earn a player points. In the case of hit circles, the points awarded are completely dependent on the timing of the hit. Sliders are generally considered more lenient, and as long as a player doesn't hit the start far too early or too late, collects all the slider ticks, and continues to hold the hit button and hover the cursor over the slider ball until it reaches the end, a maximum number of points are earned. The points awarded by a spinner are dependent on the number of spins completed. Additional spins after a spinner has been cleared will further increase the points earned. Successful hits will fill the health gauge a small amount.

No points are earned when an object has been missed. Hitting a hit circle too early or too late, failing to collect any slider ticks, or failing to fill the spinner gauge an adequate amount will result in a miss being added to a player's score. A miss, or missing a slider tick or end, causes the health gauge to drop an amount.

Scoring

A combo multiplier is kept throughout the song. Upon successfully following an object (hitting a hit circle, hitting a slider end or slider tick, clearing a spinner, etc.), the multiplier is increased by 1; upon a failure (missing a hit circle, pressing a slider start too early, missing a slider start or slider tick, or not filling a spinner an adequate amount), the multiplier is reset to 0; combo multiplier is not increased nor reset to 0 by missing a slider end or receiving 1,000 bonus from spinner. This multiplier is then multiplied by several factors including the difficulty of the played beatmap and "mod multiplier", user-applicable multiplier resulting from activating gameplay-altering mods, which is then multiplied by the base score of the hit to get the score of the hit. To be more precise, the score formula of a hit is:

Score of a hit = Base score of a hit + Base score of a hit * (Combo multiplier * Difficulty multiplier * Mod multiplier) / 25

Base score of a hit	The hit circle judgement (50, 100 or 300)
Combo multiplier	(Combo before this hit - 1) or 0, whichever is higher
Difficulty multiplier	The difficulty setting for the beatmap
Mod multiplier	The multiplier of the selected mods

Additionally, each slider start, end, and repeat tick awards 30 points, each slider middle tick awards 10 points, and each rotation of a spinner awards 100 points. Players are also awarded with additional bonus of 1,000 points for each rotation of a spinner after the spinner meter is full.

Mods

osu! has several difficulty modifiers that can alter the gameplay. These mods are categorized into four groups:

Difficulty reduction

These mods reduce the difficulty (for example, by disabling failing so a player can play even when the health bar reaches zero), but at the expense of reducing the score multiplier.

• Easy (abbreviated as EZ) reduces the approach rate, overall difficulty, and HP drain, as well as increasing the circle size. Also, the player is given three lives; that is, when the HP bar is exhausted, the game pauses and it refills up to two times. This mod multiplies score by 0.50x.^[2]
• No Fail (abbreviated as NF) makes the player incapable of failing at the expense of a 0.50x score multiplier.^[3]
• Half Time (abbreviated as HT) decreases the BPM to 75% of its original value, and increases length of the song by 33%. This mod multiplies score by 0.30x.^[4]

Difficulty Increase

These mods increase the difficulty of the map in various ways, and reward the player with an increased score.

• Hard Rock (abbreviated as HR) increases the Approach Rate, Overall Difficulty and HP Drain Rate, while decreasing circle size, mirroring the map vertically. This mod adds a score multiplier of 1.06x.^[5]
• Sudden Death and Perfect (abbreviated as SD and PF, respectively) causes HP to instantly drain to 0 if certain criteria are not met. In Sudden Death's case, the map is failed if the player ever misses, hits the beginning of a slider too early, or otherwise breaks combo. Perfect mod fails the player if his or her accuracy ever goes below 100%. These modifications do not affect score.^[6]
• Double Time and Nightcore (abbreviated as DT and NC, respectively) increase the BPM to 150% of its original value and decrease duration of everything in the beatmap by 33%. Nightcore also increases the pitch of the song and adds a rhythmic beat. In original and Taiko gamemode, this mod adds an extra 1.12x multiplier to the score. In Catch the Beat gamemode, the score is multiplied by 1.06x.^[7]
• Hidden (abbreviated as HD) removes approach circles and causes hit circles to vanish a period of time after appearing, based on the beatmap's set approach rate. Sliders vanish over time as the player continues to follow the slider track with their cursor. The player still has to click on the correct position of the note at the correct time to score a hit, as in standard play. In Taiko, Catch the Beat and osu!mania, notes disappear about halfway through the screen. Like Hard Rock, this multiplies the score by 1.06x.^[8]
• Fade In (available only in osu!mania) is an inversion of Hidden, making the notes fade in as they reach the bottom half of the screen. This mod doesn't add any score bonus, since it is unique to the osu!mania gamemode.^[9]
• Flashlight (commonly abbreviated as FL) causes the screen to go black, except for a small area around the cursor. When combo multiplier reaches 100 or 200, the field of view shrinks to a smaller area, returning to its original state if the combo is broken. This mod adds a 1.12x multiplier to the player's score.^[10]

Special

These mods are the mods that don't apply to other categories. These mods make the play "unranked" and scores achieved while using these mode are not recorded (excluding "1K"-"9K", "Co-op" and "SpunOut" mods).

• Relax (unavailable in osu!mania; abbreviated as RX) requires the player only to move the cursor, while the notes are hit with perfect timing automatically. It is impossible to fail in this mode. In Catch the Beat gamemode, this mode allows the player to use their mouse to control the character.^[11]
• Auto Pilot (osu! standard only) makes it so that the player only needs to click and cannot fail.^[12]
• Spun Out (osu! standard only; abbreviated as SO) makes the game automatically complete spinners for you, while adding a 0.90x score multiplier.^[13]
• Auto allows the player to watch a perfect play of the beatmap (with some exceptions).^[14]
• Cinema shows only background and storyboard, while automatically playing hitsounds on time. It is possible to use Double Time, Nightcore and Half Time alongside this mod. Background dim will be set to 0%, and background video and storyboard will be tuned on, while this mod is in effect.^[15]
• xK (osu!mania only) will force all osu!mania beatmaps to use the selected key setting, ignoring the original key setting of the beatmaps. It is possible to choose key settings from 1K to 9K. This mod reduces the score by 33-10%, depending on selected key setting. If selected key setting matches the original, score is not changed. This mod does not work on any beatmap that was specifically created for the osu!mania gamemode! ^[16]
• Co-op (osu!mania only) introduces a second playfield with second set of controls based on current key count (e.g. 7K -> 7K + 7K). For osu!mania specific maps, the key count is split in half, while on maps with odd key count, one set of controls has an extra key (e.g. 5K -> 2K + 3K). It is possible to increase the key count to 18K by combining Co-op and 9K mods. Note that this is possible on beatmaps, which are not osu!mania only.^[17]
• Random (osu!mania only) causes the note placement to change, while it does not affect the note timeline.^[18]

Experimental

These mods do not appear on the "Stable" build and are not recommended for general use. The following mod names are placeholder names and may change.

• Target Practice turns the game into a game as described by the title, and the speed is determined using the BPM of the selected song.

Mods with opposite effects cannot be used at the same time (e.g. Hard Rock and Easy cannot be used simultaneously). If multiple mods are used together, the final score multiplier would be the result of the multipliers carried by each mod multiplied together (e.g. if a Hidden mod along with an Easy mod was used simultaneously, the final multiplier would be 0.50 x 1.06 = 0.53).

Beatmap Parameters

Tab related to the core of beatmap's settings. Each setting affects different aspects of the beatmap.

HP Drain Rate

Known as "HP" in Edit's song selection. The rate at which HP decreases, which is always constant except during breaks. Further HP is lost with misses. HP is recovered by getting a score value and spinning spinners. More HP is recovered with Geki and Katu at the end of a combo.

Circle Size (osu!, Catch the Beat, Taiko only)

Known as "CS" in Edit's song selection. This determines the size of circles and sliders. The value range from 2 to 7 with the smaller numbers being large sizes (like needle gauges). The smaller circles make the map harder by requiring the player to be more precise. Most maps use sizes 3, 4 and 5. 6 is sometimes used and 7 is almost never used (it will be roughly the size of your cursor). 7 is likely to be seen when using the Hard Rock mod.

Key Count (osu!mania only)

Known as "Keys" in Edit's song selection. This determines the xK count for the difficulty. The value range from 1 to 9 with the selected number signify the amount of xK to be used on the difficulty. Clicking on "Co-op mode" checkbox doubles the currently selected amount (from 5 onwards), leading to 10K (5), 12K (6), 14K (7), 16K (8), and 18K (9).

Approach Rate

Known as "AR" in Edit's song selection.

General

The Approach Rate is a number (from 0 to 10) that indicates how long circles stay on the screen, from the moment they appear until the time to click on them. Higher approach rates mean that circles will be shown for a shorter period of time, giving you less reaction time to plan ahead when to click on them. Inversely, lower approach rates mean that circles will be shown on the screen for a longer time. This gives gives you more time to react to each circle, but can result in an excessive number of circles on the screen if the AR is too low.

Technical

The length a circle remains on the screen (without mods) ranges from 1800ms at AR0, to 450ms at AR10. Four mods can alter approach rate timing when activated:

• Easy: Halves the AR value. (ex. AR10→AR5 ... AR2→AR1)
• Hard Rock: Multiplies the AR value by 1.4, up to a maximum of AR10. (ex. AR3→AR4.2 ... AR9→AR10)
• Double Time: The AR value doesn't change, but the 1.5x play speed causes circles to stay on screen 33% shorter.
• Half Time: The AR value doesn't change, but the 0.75x play speed causes circles to stay on screen 33% longer.

Note: While Half Time and Double Time do not change the actual AR value, the speed difference can lead to an apparent AR as low as -5 or as high as 11. In the chart on the right, these apparent values are given to allow easy comparison between approach speeds with and without mods. Actual AR, however, is always a number from 0 to 10. Note that AR levels scale by 120ms below AR5, and 150ms above AR5.

Overall Difficulty

Known as "OD" in Edit's song selection but as "Accuracy" on Beatmap Listing page.

General

The Overall Difficulty is a number (from 0 to 10) that indicates how difficult it is to achieve high accuracy. Since accuracy is important for gaining HP, overall difficulty indirectly influences how hard it is to pass a map. Higher overall difficulties mean a smaller window of time in which one must hit a circle, both in general and terms of getting a 300. Spinners must also be spun more in order to fill up the gauge in time. Note that in some cases, raising the OD can make previously possible spinners impossible.

Technical

At OD0, one can hit a 300 at less than 79.5ms away from exactly-on-time. On the other end of the scale, OD10 requires being less than 19.5ms away for a 300. Four mods can alter overall difficulty timing when activated:

• Easy: Halves the OD value.
• Hard Rock: Multiplies the OD value by 1.4, up to a maximum of OD10.
• Double Time: The OD value doesn't change, but the 1.5x play speed causes hit windows to be 33% shorter.
• Half Time: The OD value doesn't change, but the 0.75x play speed causes hit windows to be 33% longer.

While Half Time and Double Time do not change the actual OD value, the speed's effect on hit windows will make circles seem to have a lower or higher apparent OD, respectively. In the chart below, apparent OD values are provided to allow comparison between timings with and without these mods. Note that these apparent OD values only apply to 300s on circles. Windows for 100s, 50s, and sliders (which use the 50 hit window) scale more harshly with Double Time than this apparent OD suggests, and more leniently with Half Time. Again, outside of NoMod/HR/EZ (on the left side), the OD values below are only for comparison: the actual OD value is always a number from 0 to 10.

The osu! timing system does not allow a hit circle to be hit until the previous one has been hit or its time frame has been exceeded (resulting in a miss). With a low OD, the time frame of one circle may overlap with the next. Thus, one could hit the second note with perfect timing (after failing to hit the first note) and end up completely missing both because the time frame of the first note has not been exceeded yet.

Approximate Difficulty Rating

Known as "Stars" in Edit's song selection. This is a summary of all of the settings chosen on this page. More stars mean harder maps and more score. This is not the final star ranking of the song; it is just an approximation based on the settings you chose.

Other Game Modes

osu! features three special game modes that are accessible in the mode selection of the play menu: Taiko, Catch the Beat, and osu!mania. These game modes allow a different style of gameplay from the standard play mode. These modes do not affect scores and leaderboard ranks in the standard mode and such, have separate leaderboards.

Taiko

The Taiko mode is based on Taiko no Tatsujin, another rhythm game which involves hitting drums to the beat of a music piece. Taiko mode does not require the use of the cursor except for browsing the beatmap list and the pause menu. Instead, only clicking is required, which can be done with either a keyboard or a mouse. However, the osu! community has found various ways of supporting a Tatakon or DrumCon controller intended for Taiko no Tatsujin. Usually, an external script is used to map the controller input to keys on the keyboard. A PlayStation to USB Controller bridge is required to adapt the controller for a computer.

When playing the Taiko mode, red and blue beats, as well as long yellow drumrolls (with an appearance similar to a slider) will scroll across the screen – the player gets more points for the more hits they can achieve. The red beats are referred to as "Don" and the blue beats "Katsu". The red beats represent the Taiko (drum) center and the blue beats represent the rim. Spinners are also present in Taiko mode.

Towards the left of the screen is a stationary circle. A player must hit the key(s) corresponding to each colored beat when a beat passes under this circle. Default keys are Z and V for blue beats, and X and C for red beats. Key configuration can be reviewed and changed in the Options menu, under Input. To hit the red beats, the player must hit one of the two inner hit buttons. For blue, a rim hit button must be pressed. Large versions of these notes can be hit like the normal variants, but will give you double points if you hit them with either both inner hit buttons (for red notes) or both rim hit buttons (for blue notes). When a drumroll passes under the circle, players can hit each tick marker using any of the hit buttons, but not hitting them will not penalize the player. When a spinner appears, they must alternate hitting the inner and outer hit buttons until the number at the bottom reaches 0.

Catch the Beat

This mode puts the player in control of a character (named Yuzu) holding a plate above their head, with the objective of catching fruits falling from the top of the screen.

Regular beats on a map are converted simply to fruit falling straight down. Sliders have one fruit at each end of the slider and a trail of juice drops leading between the ends. Large juice drops are the equivalent of slider ticks, while small drops add extra points to the score and affect accuracy. Spinners become fruit falling en masse from the top of the screen; the player does not need to catch all of the fruit, although catching more fruit will earn them more points.

osu!mania

osu!mania is a mode similar to Beatmania IIDX and DJMax where players need to press keys bound to several columns according to the music. As the music plays, notes are falling from the top of the screen in several columns whose number depends on the map. As a note reaches the bottom row of some column, the player is expected to press the key bound to that column to clear the note.

A special set of mods is available in osu!mania, namely 1K, 2K, 3K, 4K, 5K, 6K, 7K, 8K, 9K, Co-op, and Fade-In. Usually beatmaps are meant to be played by a certain amount of keys set for the beatmap; however, using one of these special mods (1K-9K) can change this amount of keys for a score reduction. In osu!mania, mods do not add any score bonus, since maximal score for any osu!mania beatmap is set to 1,000,000.

This mode was made public on September 30, 2012.

Beatmaps

The game uses player designed "beatmaps", which are the files containing the actual gameplay data. These are created using an in-game editor, allowing the user to pick any song they like and produce beats for it. Beatmaps for specific songs can then be shared through an in-game uploader directly linked to the main site. Players can then provide feedback for the beatmaps, referred to as a "mod", usually suggesting some means of improving its quality. After the author has modified the beatmap according to the tips it received and the Beatmap Nominators are content with its quality, they may nominate it for ranking. Beatmaps must then undergo a seven-day trial period in the "qualified" beatmaps section, after which they will be moved to the "ranked" beatmaps section. Qualified maps have a high chance of returning to pending if an issue is found by a member of the Quality Assurance Team.^[19] Statistics for each ranked beatmap are maintained on the osu! website. Scores for each ranked beatmap are totaled to determine a player's ranked score, which determines a player's score ranking.

As of April 13, 2015, over 300,000 beatmaps have been created, out of which over 10,000 have attained ranked status. The number of ranked maps gradually increase as the Beatmap Nominators rank newly submitted maps.^[20][21]

Multiplayer

On June 3, 2008, multiplayer was added to the public release (b335).^[22] Multiplayer consists of a central lobby displaying available rooms, and current online players. Rooms are created with the "New Game" button. A game begins when all players in the room are labeled as "Ready" and the host clicks start, or enough players are "Ready" that the host has the option to "Force Start". The Multiplayer game is made up of the normal components as a Single Player osu! game, but with the in-game scoreboard displaying the current rankings of the players in the room. All play modes (including Taiko, Catch the Beat and osu!mania) are available in multiplayer mode, as well as a variety of scoring rules, such as osu! Standard Score, where the highest score wins, or osu! Standard Accuracy where hitting the notes perfectly seizes the top spot. Players are also able to play tag co-op where the room works as a team to complete the song as each player is given certain beat clusters to hit, 1 player at a time. As of release b593a, Tag Team mode has been introduced where players are sided on two teams (Red and Blue) and work as one to win.

Critical reception

The game has been featured in several magazines and websites.^[23][24] The reception has generally been positive, with the biggest complaint being that playing osu! with the mouse takes a long time to get accustomed to.

Non-PC platforms

As of November 2008, an iPhone/iPod Touch osu! port was announced and was released to the general public on January 2009 via Cydia repositories.^[25]

An official App Store version of osu! entitled osu!stream was released on 08/01/2011.^[26] osu!stream does not allow for user made beatmaps to be played, instead allowing only a select number of songs that are purchasable from an in-game store.

There is also an outdated port of osu! that has been released to Android known as osudroid!. This port was originally made by a member of the osu! community known as Pesets.^[27] It has since been replaced by 3rd party ports such as opsu! or an unofficial patch for osudroid!.

At the Malaysia Comic Fiesta 2013 in Kuala Lumpur, peppy released a new peripheral, named the osu!tablet.^[28]

A version of osu! for Windows Phone 7 and 8 devices called osu!WP has also been released.^[29]

osu!stream

An official version in the Apple App Store was added for the iPhone/iPod Touch called osu!stream.^[30] This version of the game does not include custom beatmaps; instead it has both free and paid beatmaps available for download from the in-game store.

On January 3 of 2014, osu!stream was removed from the iOS App Store for copyright reasons.^[31] However, it was re-added to the iOS App Store on January 28, the same year.^[32] Since the copyright infringement letters, beatmaps with links to beatmania IIDX or Skrillex have been removed, although they can be found through external sources.^[33][34]

osu!stream has three gameplay modes:^[35]

• Easy: Slow beats, and it is impossible to fail.
• Stream: This mode is unique to osu!stream. This mode causes the gameplay to switch between "streams", or different difficulties in a single game based on the player's performance.
• Expert: Can only be unlocked if the player has achieved the ranking of "A" or better in stream mode. In this mode, gameplay is difficult with beats appearing faster, more stacking beats, more connected beats and faster drain of the health bar.

Community

The community includes over 9,079,914 registered users, with a total of over 5.31 billion ranked plays.^[36]

osu!supporter

osu! offers perks to players who contribute $4 or more. Supporters can download beatmaps directly on the osu! client through a program inside the client, named "osu!direct", and can automatically download from spectator or multiplayer matches as well as several other perks, including extra beatmap submissions and the ability to change your in-game username once at no extra cost.^[37]

osu!next

On August 1st of 2016, osu! developer Dean "peppy" Herbert announced osu!next as well as an open source osu! framework. The project includes a major overhaul of the game's GUI as well as a redesigned homepage. ^[38]

See also

• Beatmania IIDX
• Frets on Fire
• StepMania
• Osu! Tatakae! Ouendan

References

External links

• Official website
• Official wiki