I'm developing a game based off of anime like CardCaptor Sakura and Sailor Moon with a few ideas borrowed from GTA-styled games. The basic idea is that you live in Neo Crystal Tokyo 2 (latin-SailorMoon-Japan-JSRF :P) where gang vilence is running amuck. Something simular to the 4400 or C-Men or whatever where a lot of people are developing powers is happening and when the game starts, your given the choice of being a magical boy/girl, a gang member, or a normal human. Magical Girls can be on the side of gangs, but it'd be the same as an Allied soldier fighting on the side of the Mongol Horde or whatever the things are called in World of Warcraft (Warcraft is basically just CnC with mindless micro-managing, so I guess the units themselves were all Blizard had going for them [/Westwood fan-ism]). Gang members could disreguard their alternate identies entirely to be good guys, and act entirely as civilians. Civilians could fight using guns (like gangs) or scrolls (like magical girls). Note their are magiked guns (like in the one anime). Taking a page from NetHack, Things are either MNU (Magiked, Normal, or Useless). Magic can be used with scrolls (NetHack), stupid poses (err, anime), or cards (CardCaptor Sakura).

The way exp works is:

HP - Health, Attack, Defense
MP - Magic
ST - Attack, Defense
IQ - Defense, Magic scrolls
XP - Level, basically. It stands for how advanced your stats are. Ex. HP 1, MP 1, ST 1, IQ 1; XP = 0; HP 5, MP 5, ST 5, IQ 5; XP = 1; HP 10, MP 10, ST 10, IQ 10; XP = 2; etc.

Civ - Civilian
Mag - Magical Girl/Boy
GTA - Gang member
Nor - As Civilian
Dis - Disguised

Civ Nor - 100% of HP, MP, ST, and IQ to Nor; 0% of HP, MP, ST, and IQ to Dis
Civ Dis - 0% of HP, MP, ST, and IQ to Dis; 100% of HP, MP, ST, and IQ to Nor

Mag Nor - 100% of HP, ST, and IQ to Nor; 75% of MP to Nor; 100% of HP, ST, and IQ to Dis; 125% of MP to Dis
Mag Dis - 100% of HP, ST, and IQ to Dis; 125% of MP to Dis; 100% of HP, ST, and IQ to Nor; 75% of MP to Nor

GTA Nor - 100% of HP, MP, ST, and IQ to Nor; 100% of HP, MP, ST, and IQ to Dis
GTA Dis - 100% of HP, MP, ST, and IQ to Dis; 100% of HP, MP, ST, and IQ to Nor

Leveling is uncapped, meaning you have to use your IQ (as in wits, not the thing that factors into your defense) to figure out how to keep from being blown away. You lose a level whenever you die (lowest is 0, Mag Nor starts out at level 15, Mag Dis starts at level 1, Everyone else starts at level 15 in both (Civ Dis is impossible, though)). If you've played destroy all humans 2, it's simular to that, only instead of you being an alien trying to destroy the world, your a boy/girl trying to save/destroy the city and keep the others from destroying you.

The general, non-absolute formula is this:
Civilians hate gangs and sometimes magical girls.
Gangs hate Magical Girls and sometimes civilians.
Magical Girls hate Gangs.

Roleplaying will, err, play a big part in the game, as you can buy all the starting equpitment at stores, meaning that you can be a magical girl and make the gangs think your a gang member.

So, anything I can add/improve on?