Project DIVA titles are rhythm games in which players are allowed to choose from a wide variety of Vocaloid songs, original songs sung by Vocaloids, including songs sung by Hatsune Miku, Kagamine Rin and Len, Megurine Luka, Kaito, and Meiko. Players also can choose which character they wish to play in the game. Known as modules, these modules can be completely different characters or simply different costumes for the same characters. These modules, though not directly controlled by the player, will be the ones appearing in the music videos throughout the game including their specific costumes. For example, if the player chooses Kagamine Rin for their first character and Hatsune Miku for their second character, only Kagamine Rin appears in the video during solo songs, but for duets both Hatsune Miku and Kagamine Rin will appear. Each of the songs have their own difficulties, ranging from Easy, Normal, Hard, Extreme and Extra Extreme for some songs in newer games. Initially both the Easy and Normal difficulties of a song are unlocked, upon clearing the Normal difficulty, the Hard difficulty will be unlocked and so forth. Players progress through the game by completing songs and unlocking more new songs until they eventually unlock all songs. Gameplay is similar to that of other rhythm games, in which players must press a series of buttons according to the sequence on the screen. The game primarily makes use of the 4 main symbols, X, circle, square and triangle, which are the face buttons for the PlayStation Portable. Various floating gray buttons of those symbols will appear on the screen, and the colored version of those symbols will begin to float in from the various sides of the screen. The player is required to press the face button once the colored symbol lands on its grayed version and based on the player's timing their accuracy is rated. Accuracy is described with a word displayed in the bottom right corner of the screen, ranging from "Cool" to "Miss". The game is scored on accuracy and the player is awarded with a rank ranging from "Perfect" to "Dropout". It also includes a chance mode whereby the combo system compounds points earned, for example one perfect note gives the player 100 points, if they have a combo of 34 notes, the 34th note alone gives them an additional 3400 points. In addition to the game's standard rhythm game feature, user-generated content may be created in the game's Edit Mode, which allows users to create their own custom Promotional Video or Music Video, using songs already in the game or any custom MP3 format music file for the PV. Players can customize the video playing in the background, the various modules, backgrounds, costumes and even dance moves by the modules in the PV. Players can also modify the module's face to make the module appear to be singing so as to lip-sync the custom song to the video. Other than the Edit Mode, there is also a Diva's Room mode in which players can buy and obtain items throughout the game or from the in-game store to decorate their module's room with. Players can also take screenshots of their modules whilst they are playing in their room.
The series has been popular among fans in Japan, having sold over 1 million copies as of April 2012 in Japan alone. In July 2014, Sega announced that the franchise has sold a total of 2.5 million games within Japan. By November 2014, the franchise had sold 4.5 million units at retail and downloads. By March 2017, the series had sold 5.3 million units. As of 2018, the series has sold 6million units.
