Taiko is a game mode in osu! that borrows almost all of it's elements from the Japanese rhythm game, Taiko no Tatsujin (Released as Taiko: Drum Master in North America).
In this game mode, players hit the drum [a.k.a. TaTaCon if you own one, else go with keyboard] in time with red (Don) or blue (Katsu) notes on the screen. Red notes indicate that you must hit the middle of the drum (x or c on keyboard's default controls) and blue notes indicate that you must hit the rims of the drum (z or v on keyboard's default controls). Large red or blue notes indicate that you should tap with both buttons (according to colour), but if you tap with just one, you don't break combo, just get less points (300 instead of 600). It is recommended to tap large notes with both buttons. Long yellow notes indicate a drumroll of either red or blue notes (user preference, most just drumroll red middle). These do not add to your combo or cause a combo break if you choose not to drumroll throughout the entire length. However, different from Taiko no Tatsujin, there are upper limits on number of hits on the slider which is 4 times of the length of slider while it is 8 times of the length of the slider in songs that is equal or lower than BPM125. If sliders were hit too fast, no hit is recorded during slider. Therefore, it requires a good synchronicity and some note-reading to get all the drumroll hits.<
In the osu! variant of Taiko, red balloons (repeatedly hit red middle until pops) and bells(spin the analog stick) found in some versions of the console game have been removed and replaced with a shaker that mimic's the osu! spinner. This shaker requires the player to alternate between rim and middle to whittle down the number on the screen before the next set of notes appears. Unlike some other rhythm games (Read: Drummania, Guitarfreaks), players can play random notes on blank conveyor without fearing a point deduction, as long as no other notes are not on your judgement circle.
In Taiko mapping, red notes refer to no hitsound Hit Object, while blue notes need a whistle or a clap on a hit circle. Large red notes need a finish, while large blue notes need both finish and whistle together. Slider represents long yellow note (also known as drumroll) and spinner represents shaker. When mapping taikosu! (Standard Diffs which are supposed to be played on Taiko) or authentic maps (copied maps out of the Taiko no Tatsujin game), note that short sliders (usually less than a beat) are converted into ordinary circles in Taiko mode unless the map is set to Taiko-only. For maps with 125 BPM or lower, 1/8 drumrolls are given instead of 1/4 drumrolls. As 1/8 rhythms may not appear in the music, it's not suggested to place slider in this case. Note that 1/6 drumrolls are given if slider tick rate 3 is used.
Song accuracy is calculated by the sum of all notes accuracy divided by the number of notes. A GREAT (良) counts as 100%, a GOOD (可) as 50% (half) and a MISS/BAD (不可) as 0% (which breaks the combo).
Taiko uses the same grade system as osu!'s Standard game mode. In a full-combo attempt, since GOOD always counts as 50% (unlike in Standard), you can easily tell whether you're going to get a S, A or B just by looking at the accuracy counter:</p>
* S - 95% above (90+% GREATs, or less than 1 GOOD for every 10 notes) * A - 90% above (80+% GREATs, or less than 1 GOOD for every 5 notes) * B - 85% above (70+% GREATs, or less than 1 GOOD for every 3.33 notes)
Each GREAT is worth 300 + RoundDown(Combo / 10) times n up to a maximum of 300+10n points in which n depends on the difficulty rating of the song. A typical value of n (4.5-5 star difficulties) is 80, which gives a maximum score of 1100 at later combos. For 4-4.5 star difficulties, n is equal to 64 in which the maximum score per hit is 940. In the hardest case n is equal to 96 in which the maximum score per hit is 1260. Yet there are lower value of n for even easier difficulties.
Each GOOD gives half of the score as GREAT does, while zero score is given for MISS/BADs. Double score is given for successful hit large notes (different from Taiko no Tatsujin, left and right drum must be hit at the same time very precisely in order to allow a successful hit of large notes). For yellow long notes, 300 is given per hit in the small one while 600 per hit is given to the large one. For shaker notes, each shake gives 300 and finishing the shaker gives score twice as much as a GREAT of the current combo.
Unlike osu! or CatchTheBeat, a miss in Taiko will not reduce the score from maximum possible score greatly. Instead, constantan score is reduced per miss if each miss is separated by more than 100 combos (with the existence of shaker and large notes, score loss would be larger). For example, in a typical difficulty, breaking a combo in the middle of a song, without accounting for large notes and spinners, would result in a maximum loss of 44,000 points (to bring the combo back up to 100).
Also unlike the other game modes, Kiai Time has an effect on scores because it refers to the "Go-Go Time" in Taiko no Tatsujin. While Kiai Time is active, the drum in the upper-left changes animation (named pippidon or Don/Katsu in Taiko no Tatsujin), the playfield has a background gradient and the hit area gains a fire graphic around it. Additionally, all hit notes gain a 1.2x score multiplier, long yellow notes included, except for hits on a shaker (the final hit is still multiplied).
It is possible to hook up a TaTaCon drum controller, which are primarily made for the home ports of Tatsujin and Drum Master.