Hatsune Miku and her merry friends.* From left to right, Kagamine Len and Rin, Hatsune Miku, and Megurine Luka. Not pictured: Kaito and Meiko.
It started with one dot...
Hatsune Miku: Project DIVA is a series of Vocaloid-themedrhythm games released by Sega. As the title may very vaguely imply, Miku is front and center, although the other Crypton Vocaloids, Rin, Len, Luka, Meiko, and Kaito, get their share of the spotlight, as well.The aim of the game is simple. Notes fly toward stationary targets on screen and you press their corresponding buttons when they overlap the markers. This task is spiced up by detailed, unique 3D music videos for each song, as well as quite frankly ridiculous bonus difficulties. The series finally made its overseas debut in August 2013 with Project DIVA F, with the budget re-release of the Vita version following in 2014, but the other games are relatively import-friendly.* Excepting the 3DS Project mirai titles, due to said system being region locked.
Main series games
Hatsune Miku: Project DIVA (PSP, 2009)
Hatsune Miku: Project DIVA Dreamy Theater (PS3, 2010)* PSP connectivity DLC that lets you play unlocked songs in HD.
Hatsune Miku: Project DIVAF* Note the use of the capital F rather than a fortissimo (PS3, 2013)
Hatsune Miku: Project DIVA ƒ:Best Price Edition (Vita, 2013) * A re-release of ƒ in the same ilk as the # version of 2nd, with updated graphics and added content. Available in English as a digital download in 2014.
Attractive Bent-Gender: Len is all-too convincing as a girl when wearing his cross-dressing outfits. Ditto for Rin making a convincing boy in hers.
Break Up Song: "Koi wa Sensou"* "Love is War" from the first game is about a particularly bad break-up, sung from the break-uppee's perspective. "Just Be Friends" from 2nd and extend is a softer example, sung from the break-upper's perspective.
Call Back: In "Time Machine", the two toys that caused the dream from "Gigantic Girl" are sat on the floor of the treehouse.
The Dev Team Thinks of Everything: There are several songs in F where, even though a character may not appear as a selectable module, s/he will still appear in the song. If you select a Vocaloid other than the default, the default character will replace the selected one within the song. Taken to another level in "Rin-chan Now!", where the selected character's name and color appears correctly on their Twitter-like feed.
The Song "Tell Your World" was originally created for Google to advertise how Hatsune Miku has become a worldwide phenomeon. In the first Project Diva game to come to the West, the song is included. Say it with me. A song made to advertise Miku's popularity worldwide is included in Miku's first worldwide game release.
Duet Bonding: "World's End Dancehall" from ƒ has Miku and Luka facing off in a heated dance battle, only for them to hit it off at the end when they realise the crowd loves it.
Early-Installment Weirdness: Those used to later games may be put off by the first game's lack of Extreme mode, "hold" notes, and songs that aren't performed by Miku.
Likewise, games before F did not contain star notes, Technical Zones, Chance Time bonus scenes, customisation items... or rock paper scissors.
Easy-Mode Mockery: Playing on the Easy difficulty in F prevents you from unlocking the Hard versions of songs, and some modules and items. Additionally, if you choose to use a help item, the rank shown will have a green heart beside it. Some help items go further and automatically give you the CHEAP/LOUSY rating regardless of performance, preventing you from unlocking new songs.
Fission Mailed: Obtaining the Chance Time bonus in "Sadistic.Music Factory" leads to the bad ending that involves failing to escape from the factory.
Follow the Leader: 2013 saw the release of Megpoid the Music#, a similar rhythm game for the PSP featuring the popular Vocaloid GUMI.
Gameplay Grading: Being a rhythm game series, this is obviously present, though with worded grades rather than letter grades. From worst to best, they are MISS×TAKE (DROP×OUT in F's English release)* fail to finish a song, CHEAP (LOUSY in F's English release)* finish a song but fail to get enough rank points, STANDARD, GREAT, EXCELLENT, and PERFECT.
Grass Is Greener: "Negaposi*Continues". Turns out living in a video game isn't all it's cracked up to be.
Intercourse with You: A lot of the songs. To name a few, there's "magnet", "Romeo & Cinderella", "Hm? Ah, Yes.", "Iroha Uta"...
Jiggle Physics: Meiko and Luka got it going on in ƒ. Even the modestly-endowed Miku gets in on the action, depending on the outfit.
The game even uses some jiggle physics on the hair of Miku, Luka, Haku and Neru, so their ponytails bob about almost realistically.
Licensed Game: In two ways. It's themed around the Crypton-produced Vocaloids (this unfortunately means no Gumi or Gakupo, for instance) and a few fan derivatives, and technically, every single song is a licensed song, since they're preexisting songs made by producers who are not SEGA or even Crypton staff.
Which made the localization of Project Diva F a shock to all of Miku's fans, especially since none of the songs are cut.
Life Meter: Like in many other rhythm games. However, you also need to finish the song with enough Grade Points (or, in earlier games, at least a certain percentage of COOL or GOOD judgements) to clear the song properly.
Logo Joke: The logo screen has Miku singing "Se-gaaaa!", similar to how older Sega games had the "Se-gaaaa!" yell.
Later games had Rin, Len, Luka, Kaito and Meiko join in randomly.
Love Triangle: "Acute" from F has one between Kaito, Miku, and Luka. As if to drive the point home, the stage is even shaped like a triangle!
Mercy Invincibility: In DIVA Arcade, you're granted a brief period of "safety" at the beginning of the song; your Life Meter is restrained from falling below a certain amount until the safety wears off.
Motor Mouth: To varying degrees based on the song, from short spurts in Secret Police to constant and nigh-indecipherable in Rin-chan Now!.
Mini-Game Credits: In F's closing credits, you play as Hachune Miku, throwing leeks at the credits to score points. Amusingly, after the first play, you can buy an item that lets you play it whenever you want, and new features are unlocked as you play the credits game multiple times.
No Export for You: Finally averted with Miku Flick and Project DIVA F, both versions, although the PSP and 3DS games remain Japan-only. DIVA Arcade had location tests in San Francisco and Los Angeles, but that's about it.
Project DIVA f for the PS Vita was announced in Sega's blog to be localized in the future, thus will be subequently averted as well.
Nostalgia Level: Project DIVA F2nd brings back updated versions of past songs, such as "Packaged" from the first game, "Romeo & Cinderella" from the second, and "A Thousand Years' Solo" from extend.
This extends to the modules in the same game, with confirmation of the Nyanko and Heart Hunter modules from the PSP games, the latter being well known due to it's use with the first game's rendition of Ura Omote Lovers.
The game runs at 60 frames per second instead of 30. Not even Project DIVA F on PlayStation 3 runs at more than 30 FPS.
Holds are no longer mandatory. Holding a hold note down simply gives you bonus points, up to 3000 per hold note if another note of the same button doesn't appear early enough to interrupt the hold.
"Chord" notes now use different buttons. On harder difficulties, chords of 3 and 4 buttons are not uncommon.
Normal mode actually uses all four buttons.
Old Save Bonus: Having the original game's save on your memory stick will net you all of its costumes for free, plus an exclusive DIVA Room poster and title, in the sequel. Likewise, having a 2nd save will get you all of its costumes and such for extend.
The first scoring system is the traditional points system. You get points for hitting notes on time, and you also get bonus points for hitting notes during Chance Time and holding down notes.
The other is the Grade Point system, which is simply an overall percentage of your note accuracy, with a few bonuses for completing Technical Sections and Chance Time.
Self-Imposed Challenge: Some of the rhythm game items you can choose will make the song harder in various ways, ranging from making targets appear much later and preventing recovery of your life meter.
Shout-Out: "Remote Controller"'s BGA features a Sega Dreamcast controller, which replaces the Famicom controllers in the original PV because you can probably guess how Sony would feel about Nintendo copyrights in games on their systems.
Several of the Project Diva intros feature a Yamaha DX 7 synthesizer, including Project Diva F revealing Miku's one has the voice settings for 37-39 read 'Best Friends Forever'.
Sibling Rivalry: "Remote Control" in F just screams this for Rin and Len, though they most-often get along very well in their other duet songs.
Translation Correction: Some slight instances of Engrish were corrected for the English release of F. For example, "Rest X Notes" seen during a Technical Zone became "Notes Left: X".
Updated Re-release: 2nd# fixes several bugs and niggles, speeds up load times, and comes with a free DLC code that gives you all of extend's costumes to use. extend could be considered this to 2nd, especially seeing as how it's working title was Project DIVA 2.5. In a more traditional example, F is a re-release of ƒ.
Variable Mix: Missing a note in newer games will cause whatever vocals corresponding to that point in the music to not play. Miss notes repeatedly and the characters will sound like they forgot the lyrics.