Extra: Generic High school Romance, Knows it's generic and has fun with it. Does get emotional at the end concerning the 2 lead heroines. Important in that it develops the Characters and shows how Fucked up the Unlimited world is.
Unlimited: WTF? alternate dimension out of the blue. (important to note Male lead, Takeru, remembers the Extra dimension)Fortified with Aliens and Mech. Not as 'fun' as Extra but necessary to set the the Stage for Alternative.
Supplement: basically a fan disc, primarily serves to 'supplement' Sumika's lacking end in Extra. Card game, extra character development, etc.
Alternative: Another Alternate Dimension/universe. Takeru has new game+ skills and Humanity gets it right this time, Made of Death, Gar, Death, Gar, and a little more death.
Altered Fable: Extra-ish dimension with Alternative characters added to the mix. Made of lulz and porn, lots of porn.
Total Eclipse: side story set in the Alternative dimesnion, honestly, haven't payed attention to it.