beatmania IIDX 3rd style is the first PS2 release in Konami's long-running beatmania rhythm game franchise, and the first home release from the IIDX series. This version contains a selection of tracks from the first four arcade IIDX games -- beatmania IIDX, IIDX Substream, IIDX 2nd style, and IIDX 3rd style -- for a total of more than 80 songs, though it does not feature a complete selection of songs from any specific arcade version.
beatmania IIDX is very similar to the previous beatmania games, with the distinct difference of the controller having seven keys -- four white and three black -- compared to the original series' five. In each song, color-coded notes scroll from the top of the screen in time with the music, and the corresponding keys must be pressed at the correct time to play along with the music. Good timing will increase the player's Groove Level, while poor timing or missed notes will decrease it, and the goal is to have the Groove Level above a certain level at the end of the song.
There are three main modes in the game. Arcade mode is presents a selection of so-called "courses" which consist of five songs each, which must be cleared in order. Free mode allows any track played in Arcade mode to be freely replayed. Practice mode is exactly what it sounds like: a practice mode where songs or sections of songs can be practiced without any risk of failure. There are also a large number of unlockable songs and courses, and numerous modifiers that affect the note charts and displays.