DJMAX is a series of rhythm action games developed by Pentavision, a South Korean developer. The first game in the series, DJMAX, commonly known as DJMAX Online, was a PC only title, whilst several sequels have been spawned on both the PC and Playstation Portable.
The DJMAX series of games is very similar in gameplay to Beatmania IIDX and Beatmania, two rhythm action game franchises created by Konami, primarily for release in Japan. Horizontal lines, also known as notes, descend from the top of the screen to the bottom where they reach a target area. As they reach the bottom, the player has to hit the corresponding key on the controller (Either the PSP face buttons, shoulder buttons and d-pad or specific keys on a keyboard) in order to play a 'key sound'. A key sound is a small part of the song being played, so if the player hits all the notes sucessfully, they hear the entire song correctly. Players can choose how many different buttons they want to play with; in the various DJMAX games, anything from two button play up to eight button play is available, with the exception of three and seven button. Players are judged on their accuracy in hitting notes, given a percentage accuracy. 100% is a perfectly timed press, whilst the game scores anything less accurate at 10% intervals, so 90%, 80% all the way down to 10% and finally 1% then a complete miss.
DJMAX also uses a 'Fever' system, vaguely similar to Star Power from the Guitar Hero series. Players can trigger Fever mode after they have sucessfully hit enough notes, causing the game to raise their score and combo multiplier by one. The highest level of Fever varies from game to game, with newer games featuring a maximum of seven over the previous maximum of five. Whilst Fever mode is activated, if the player does not trigger the next level of Fever quick enough, their multiplier is reduced back to one. Depending on the version of DJMAX, this either happens after the player has hit a certain number of notes, or after a set amount of time.
There are various play modes in the DJMAX series. Most games have a standard play mode, where the player plays four songs in sucession using the number of keys of their choice, a challenge mode, where the player plays a specific set of songs in order to achieve a preset criteria to pass, and modes for playing back the songs and music videos featured in the game. DJMAX games are feature significant numbers of unlockable bonuses, from extra songs and skins, additional modes of play, modifiers to existing gameplay and assists to aid the player in achieving better scores or passing harder songs.
As of the 25th of December 2008, Konami's Korean division is taking legal action against the creators of the DJMAX franchise due to similarities between the Beatmania series of games and the DJMAX titles. The original press release is available here in Korean, whilst a Google translated version is available here. The case called into question the interface used in the PC and PSP versions of the franchise as well as the keysounding implementation across all games and their similarities to beatmania. This case was settled out of court with production of the franchise unaffected in the end. Details on the settlement are scarce but it's known that Pentavision pays Konami a fee for any DJMAX games released prior to the lawsuit, and Konami has optioned the rights to release the arcade DJMAX TECHNIKA franchise in Japan.