Game levels, called beatmaps, are created and submitted by users via a Level Editor. These can later be refined through community modding if the creator requests it and gets ultimately approved by members of the Nomination Assessment Team and the Beatmap Nominators.
Ranked beatmaps give Performance Points (or pp, for short) after being beat, giving more pp the better you did in the map, and they also get a scoreboard featuring the best scores done in it. The beatmaps also give experience points based on how you much you scored in them, but the levels do nothing and are ultimately cosmetic.
Besides the Ouendan/EBA gameplay, osu! includes three additional game modes: one based on the Taiko no Tatsujin series, one based around the gameplay of beatmania IIDX / O2jam and one based around the gameplay of EZ2DJ's EZ2Catch mode (where one tries to catch falling fruit).
Apart from Solo mode, players can compete in all four modes in online multiplayer matches in rooms which can contain up to sixteen players, in single or team battles, in order to get the highest score, accuracy or combo possible, or play beatmaps together by taking turns between combos, depending on the room settings. In osu!mania, two players can play locally using the same keyboard.
It has an official remake codenamed osu!lazer, which will be released as an update to the stable client. It is rebuilt from ground up using a new framework that improves visuals, performance, and flexibility for future changes. It also has a new UI design and new quality-of-life features not present in the stable client. It is currently under heavy development, and currently available for Windows, macOS, Linux, Android, and iOS.
Tropes for The OT! Book, a collaborative fiction project started in the forums of the game can be found here.
Make sure to type it as "osu!"
This game provides examples of:
- all lowercase letters: The game is called osu!, not Osu! nor OSU!
- Anime Theme Songs: Around 1/3 of all the ranked maps are these.
- April Fools' Day: The jokes each year revolve around changes in the game's genre ("Touhosu", a Touhou Project/osu! hybrid), gameplay ("osu!core", where the songs in every beatmap had their pitch and speed increased), staff (unexpected demotions or promotions), and beatmaps (pretending to approve and praise an extremely poorly made beatmap).
- Also, some of those jokes have ascended. osu!core became a permanent available mod called Nightcore, and Touhosu! has been confirmed as in development by peppy.
- Call a Hit Point a "Smeerp": The currency of this game is called "kudosu", and is earned through modding unranked maps.
- Crossover: The beatmap for Queen's Don't Stop Me Now is based on the plot of a Fan Fic which combines Phoenix Wright with Elite Beat Agents. It's as awesome as it sounds.
- Determinator: A player can become this if they're trying to pass, get an FC (Full Combo), or enter the Top 50 on a beatmap, especially if the beatmap is pretty difficult. If they lose a rank in the top 50, don't expect them to quit playing for hours until they beat the player who beat their score.
- Easier Than Easy: Some maps like this like to add difficulties that aren't even 1 star.
- Fake Difficulty:
- On mapping side, it's HEAVILY discouraged nowadays, and maps with it have a very low chance of being ranked. Using solely tricks like low (or high) Approach Rate, high HP drain, etc., are no longer acceptable in the Ranked Beatmaps section. In addition, some very specific mapping techniques are not allowed to be ranked due to being very confusing and frustrating for players. A list of these can be found here
- There was a time when maps could be impossible to S-rank, even by Auto.
- Or have FAKE SPINNERS in the storyboard.
- Playing for score? Aside from the combo multipliers practically encouraging restarting over one mistake (a game design element shared with osu!'s source game), modifiers add to your score, most notoriously the modifier that increases the song's speed by 50% to give a 12% score boost. So to get high-ranking scores you have to alter the song.
- Fun with Acronyms: GMT (Global Moderator Team), NAT (Nomination Assessment Team).
- Also, some teams that don't exist anymore, like the QAT (Quality Assurance Team), MAT (Modding Assistance Team), and BAT (Beatmap Appreciation Team).
- Game Within a Game: Taiko, Catch The Beat, and osu!mania modes.
- Grade Inflation: As in Ouendan and EBA, S comes after A, but a perfect performance in osu! earns the player an SS rank. An SS achieved under the Hidden and/or Flashlight mods has a separate sprite (alternate colouration in the official skin) and commonly referred to as "SSH".
- Idiosyncratic Difficulty Levels: Beatmappers can name the difficulties of a beatmap set into whatever they like. However, Non-Indicative Difficulty names on a beatmap set's lower difficulties render it unrankable.
- Harder Than Hard: Many beatmaps have an Insane difficulty, and some even have a difficulty above Insane (officially named "Expert").
- "Oni" and "Inner Oni" respectively for Taiko beatmaps.
- Interface Screw: The Hidden and Flashlight mods. Hidden makes it so that incoming circles disappear before having to be clicked on, and Flashlight darkens the area around your cursor so you can't see incoming circles clearly.
- Level Editor
- Letting the Air out of the Band: Occurs on a failure. There's a grinding sound, and the music track slows down as it stops playing. Any visual beats also collapse and fade as well.
- Mascot: pippi.
- Marathon Level: There are a handful of "marathon" beatmaps, commonly ranging between 10-15 minutes in length, with some even longer:
- Nintendo Hard: Thought Elite Beat Agents and Osu! Tatakae! Ouendan were hard? You haven't seen anything yet. The hardest songs from Ouendan/EBA are approximately 3.5 stars on the revised star rating scale released in mid-2014 (the difficulty range that would be considered appropriate for an average osu! player is 4-5 stars, by the way.), and these games are already Nintendo Hard on their own. The hardest songs on Osu takes this up to eleven, with revised star rating exceeding 7 stars, such as "Can't Defeat Airman". Such crazy streams and jumps do not exist in the original Ouendan/EBA games. Certain maps can even have 10 to 11 stars.
- A common joke between pro players (rank 1000 or less) is saying they have problems passing "Can't Defeat Airman", there are a few beatmaps where almost all players have to struggle, such as "xi - FREEDOM DiVE (FOUR DIMENSIONS)", or "IOSYS - Utage wa Eien ni ~SHD~ (TAG4)". (Though that one is meant to be played by four players simultaneously.)
- Prior to the mid-2014 update of difficulty calculation system, original star rating scale could not keep up with the escalating difficulty of the newer beatmaps with topped off at 5 stars.
- There are the few maps that completely break the old star rating system, such as xi - FREEDOM DiVE, where the hardest difficulty is rated at around 2.5 stars, which is the average Easy difficulty rating, and the other, also insane+ difficulty is rated at 4.5, which is a typical Hard difficulty. Certain maps with high difficulty settings go ABOVE the 5.00 limit (although not by much).
- Adding on, there are several joke maps with star ratings into the negative and beyond, even reaching up to -infinity/5 in some weird special cases.
- For osu!mania 4-key, there are some maps that, while they would only be maybe a 6 star map in osu!mania, they could go up to 20-footers in Stepmania (like That Was Too Slow [4K MX] or miracle 5ympho X [Black Another]). An 8.5-star map might be around a 26-footer or harder, something like Kinetic or UKF Dubstep VIP in Stepmania.
- Non-Indicative Name:
- The Double Time modifier multiplies the speed of the song by 1.5x.
- The Half Time modifier multiplies the speed of the song by 0.75x.
- No Plot? No Problem!: Just click the circles to the beat.
- One-Hit-Point Wonder: The following modifiers do not increase score, and considered to be convenience modifiers for players who are going for a (perfect) full combo run to quickly restart the beatmap:
- In the Sudden Death mod, you fail the beatmap you're currently playing if you screw up once.
- With the "Perfect" mod, you lose instantly if your accuracy goes below 100% at any point.
- Sometimes, the HP drain on certain maps are so high that even missing one circle or note is guaranteed to throw you off and cause you to fail.
- Pinball Scoring: In standard mode, the maximum possible score of very long beatmaps with huge note counts can grow to very large numbers. In one extreme example, the very long "Within Temptation - The Unforgiving described in Marathon Level above has 10-digit scores in the top four ranks (as of this edit). To get good scores in any given map, getting a full combo is crucial. Tournaments instead use the "scorev2" system with a maximum 1,000,000 points and avert this trope.
- Power Creep: To a certain extent. The players are getting better, of course, but there are also more and more maps that can be "farmed" to earn PP. At the end of 2014, the highest PP score was 558. At the end of 2015, it was 667. In the first month of 2016, there have already been five scores that have been higher than that.
- Rage Quit: A common practice to avoid submitting and saving low accuracy scores, though that doesn't work anymore.
- Rhythm Game: The entire premise of the game.
- Ridiculously Difficult Route: On osu!taiko, turning on the Hidden and Flashlight mods makes all of the notes unable to be seen, making the player play the entire map from memory. There's a reason you only really see this combination being used in only 1-2* maps.
- Scoring Points: There are two scoring systems: the "PointValue x (combo + ConstantA) x (ConstantB)" system used in the source games, and the "pp" system (which gives a score according to how impressive the play was). There are also scoring systems that are exclusive for multiplayer matches, such as accuracy (percent-based system, which is the average accuracy for each note, being a 300 a 100%, a 100 a 33.33%, a 50 a 16.66% and a MISS a 0%), and Combo (the player with the biggest combo the moment when the map ends wins). In a multiplayer match, you can choose which system to use for ranking.
- Self-Imposed Challenge: Using one or more of the difficulty increasing mods and/or going for SS (100% accuracy) runs.
- Stylistic Suck: NotShinta's cover of Imogen Heap's Aha! is awful. Yet so very good. Notable for being the beatmap with the lowest user rating on the site.
- The Jarto series is based on this trope, having an... odd narrative told through Stylistic Suck storyboards.
- Spinsmith also has his series of bad song covers.
- ztrout is like Aha?, except it came first.
- Super-Deformed: Miniature versions of pippi, Ryuuta, and J could be found on the homepage and Catch The Beat, but were later removed.
- Unwinnable Joke Game: Several maps, such as "Centipede" (Knife Party), are designed to be impossible for human players to full combo on, lest earn a "B" rank, with multiple circles to hit at the exact same time. Not that it means the mentioned map isn't pretty to look at.
- Video Game Perversity Potential: Thanks to the versatile beatmapping and skin customization features, you can make the game display anything you want, though the really inappropriate beatmaps/skins cannot be shared on the official site.