project diva x is a 2016 rhythm game developed by sega & crypton future media and released for the psvita and playstation 4. it's the 10th entry in the project diva series, which anyone familiar with hatsune miku and other vocaloid would already be familiar with.
what distinguishes project diva x from other project diva installments is its somewhat story-driven gameplay- this being the feature of the game that, to me, makes it the best installment in the series.

Gameplay
while project diva x still contains the same "freeplay" mode standard for all project diva titles, it introduces a new mode exclusive to this installment called "live quest". within live quest, you help hatsune miku and the other vocaloids by gaining a specific amount of voltage for each "cloud", which is themed after a specific atmosphere (cute, cool, elegant, quirky, and classic). each cloud contains 4 songs and one "medley" unlocked upon completing the prior four songs. all songs in a cloud follow the cloud's theme- for example, the songs within the "cute" cloud all have a cute atmosphere.
alongside the live quest, otherwise known as "cloud requests", are "event requests", which unlock over the course of the player gaining voltage for each cloud. these event requests can range from character-specific requests, which reward the player upon completion with a rare module for its specific character, or generalized "music festival" requests, where the player chooses a handful of songs to play through with characters of their choosing.
both of these gameplay modes include visual novel-esque interludes involving different vocaloid, typically following a story. for example, during the players' first playthrough collecting voltage for the quirky cloud, miku, len, and rin try to understand how to cultivate a "quirky" atmosphere for their concerts.
the final, and in my opinion, best feature of these new gameplay modes is the change in the "modules" system. in previous project diva games, particularly those on the psvita and psp (which are the only other project diva games i have experience with), modules, or different outfits for vocaloids, are unlocked upon completion of a song, with the modules you unlock being preset for each song. for example, miku's "chat noir" module is only available upon completion of envy cat walk.
in project diva x, successful completion of any song's "chance time" will unlock a random module specific to the vocaloid you played the song with. the main factors in which module you randomly unlock depend on the song's aura (quirky songs will grant quirky modules), and the effect of the module you selected to play the song with (some modules have effects such as "increase chance of a new module" or "increase chance of a rare module"). each song has a specific "rare" module exclusive to that song, and then a handful of "common" modules you can get with any song.
this element of randomness within the module system allows for more incentive for the player to replay specific songs, in an effort to collect every module for their desired vocaloid. i really, really appreciate this addition to the module system. i'm a huge fan of gacha games, and project diva x's inclusion of a gacha system that hinges on gameplay rather than money is really, really nice.