Beatmania IIDX

Beatmania IIDX is a series of rhythm video games, that was first introduced by Konami in Japan on February 26, 1999. IIDX has since spawned 23 arcade releases and 14 console releases on the Sony PlayStation 2 It is the sequel to the beatmania game series, and part of the Bemani line of music games. A PC release titled beatmania IIDX INFINITAS has been announced, and began alpha testing in September 2015.

Gameplay General
In IIDX games, players recreate the musical score of songs available to them through the use of a DJ simulating controller.The player must coordinate their hands in order to hit the correct keyboard buttons, spin the turntable, or a combination of both in correspondence to color-coded notes that approach the judgement bar displayed on screen. Notes are divided on screen by columns which separate them accordingly to match the seven buttons and the turntable on the DJ simulating controller. As a result of hitting notes, different sounds are then produced throughout a songs duration. Correctly hitting notes will produce an accurate musical score, while incorrectly hitting notes will produce inaccuracies and mistakes in the music.

Starting from IIDX 17 SIRIUS, two new note types are added. Charge Notes is a note that must be pressed and released on the right time, while Backspin Scratch is a scratch note which require the player to spin the disc in a direction, then spinning it in the opposite direction at the end. Both are valued two combos; one for the beginning note and one for the ending note. beatmania IIDX 23 copula introduced a variation called Hell Charge Notes, which refill the gauge when held down but rapidly deplete it when not. Unlike regular Charge Notes, they can be pressed at any time, though missing the timing window will still break the player's combo.

Difficulty
From beatmania IIDX to beatmania IIDX 4th Style, song difficulty ranged from Level 1 to Level 7. beatmania IIDX 5th Style introduced flashing Level 7s as the new top difficulty. Flashing 7s gave way to Level 8 difficulty in beatmania IIDX 10th Style, and Level 8+ was added in beatmania IIDX 11 IIDXRED. The version immediately after, beatmania IIDX 12 HAPPY SKY, introduced a new difficulty scale, from Level 1 to Level 12, which has remained the standard.

Extra Stage System
Like most BEMANI titles, Beatmania IIDX has Extra Stage and One More Extra Stage songs, commonly known as ES and OMES respectively. When Extra Stage was introduced in beatmania IIDX 3rd Style, there was no new song to unlock, and the player simply got to play an extra song. Beatmania IIDX 7th Style was the first to have an unlockable song only available on Extra Stage, and also introduced the One More Extra Stage. Obtaining the secret ES and OMES required meeting certain requirements during a session of play. Beatmania IIDX 13 DistorteD was the first title with an Extra Stage system exclusive to players using an e-AMUSEMENT pass; it also included multiple Extra Stages that had to be cleared under certain requirements to unlock the One More Extra Stage.

Beatmania IIDX 14 GOLD saw the return of the standard ES and OMES songs, alongside another multiple Extra Stage system. The setup of having two systems per game (standard system and e-AMUSEMENT system) continued until beatmania IIDX 18 Resort Anthem, where the standard ES and OMES stood alongside a new song unlock system tied to a player's e-AMUSEMENT pass.IIDX 19 Lincle brought back the multiple Extra Stage system, in the form of Lincle Kingdom, while retaining the standard ES and OMES setup.Beatmania IIDX 20 tricoro replaces the standard Extra Stage with "LIMIT BURST", which allows seven different Extra Stage songs to be played. There are no One More Extra Stages for LIMIT BURST, and so far, the only OMES was Plan 8, part of Tricoro's first song unlock system, LEGEND CROSS.<

Most Extra Stage songs debut in their respective Beatmania IIDX games, but there are some Extra Stage songs (esp. from the multiple Extra Stage systems) that are crossovers from other BEMANI titles; for example, IIDX 20 tricoro's LIMIT BURST system is largely made up of notably difficult songs from other games. Examples include "neu" from pop'n music 15 ADVENTURE, "JOMANDA" from jubeat copious, and "New Decade" from Dance Dance Revolution X2, which got a specially cut version of the song for its IIDX chart.