So the idea of "body horror" as a genre or generic marker is that you are being transformed into something intrinsically and personally monstrous and everything is terrible. Right? So I figure the reverse of body horror is when you are transforming yourself into something (conventionally) monstrous because it's awesome and beautiful.
Ask me about my reverse-body-horror magical girl fighting game idea sometime.— Motor Sprite (@nfagerlund) April 26, 2013
And the core idea of the magical girl genre is about undergoing a transformation into a prettier and more perfect version of yourself -- becoming more capable and self-actualized, then performing that capability aesthetically (prettier) and through ritual combat against physical embodiments of negative and destructive psychic forces (more perfect).
I figure? After the first time you have to defend your friends' lives by going toe-to-toe against a monster-of-the-week, your idea of "pretty" is going to change pretty damn quick. Fast and strong and efficient and shiny and bulletproof, and taking down a demon before it even gets a WHIFF of your designated love interest; THAT's pretty. And thus, our heroine's mystic-gem-fueled magical girl transformation gradually becomes more and more inhuman, but, and here's the thing, she is totally cool with this, because she A: has a job to do, and B: is in the process of adopting an aesthetic of function. And the monsters of the week are stuck dealing with eight feet of shiny glittering motion-blurred blade-fingered lantern-eyed (ribbon-bedecked, glass-armored, short-skirted, and let's be clear here, you get a super-legit sparkly transformation sequence before each battle) insectile terror.
Combat system: more or less fungible, though I've been wondering about the possibilities of a top-down Secret-of-Mana-esque combat system with multi-touch interface. (Tap to neutralize attacks coming from many directions at once, swipe to attack/move, double-tap to jump across the field quickly and tap-hold to move from area to area, power up supers by attacking repeatedly/blocking repeatedly/tap-holding on yourself, then aim them by tapping several targets before the timer runs out.)
Structurally, it'd be a boss rush, with a focus on environmental movement/evolution in each encounter. Most bosses would be malignly-transformed humans whom you need to free from the negative influence that's gained control of them, and part of the magical girl genre is the corruption and unsafe-making of mundane spaces/environments, and a cool way to bear down on that is to have areas get more fucked-up and nightmarish over the course of the battle. Some bosses would have mobs of mooks to throw at you, but it's mostly about you, the enemy, and a shifting arena. Encounters would be punctuated by walk-and-talks and cutscenes in your high school or around town, probably with dating-sim elements thrown in because we have a genre to uphold here.
Speaking of genre: the traditional rhythm of a magical girl fight scene is that you transform and come on strong, get overpowered and trapped by the enemy, break free via either an assist from your allies or a recapitulation of your inner strength (depending on where in the season we are), and triumph with a glittery super-move. Here is our mutation mechanic: every time you defeat an enemy, your magical gem (which probably has a personality of its own) absorbs its power, but you don't use it right away. Instead, halfway through each boss encounter, when you get overpowered and all hope seems lost, you get to make a choice of how to spend the last boss's power and get stronger--
("Urgh! I need more speed, I can't get a claw into her! If I could just keep up, she'd be mine!" // "My hits keep glancing off! I know I can get a lucky shot in sooner or later, I just need to make sure it DOES something!")
--and then you get to fight the second "real" half of the fight with your upgraded powers. That gives us a branching skill tree that maps to a visual mutation tree. And the player becomes invested in the inhuman mutations the same way our heroine does, because that's your combat build that you built, isn't it pretty? Look what you can do with it!
And THAT is my reverse-body-horror magical girl fighting game idea. Buffy minus some angst plus some camp times Sailor Moon divided by Bleach. Shout-outs to that tossed-off line in Possession where they were discussing the Melusine poem and mentioned that the monstrous fish-form was beautiful, to a conversation on Twitter I caught the tail-end of where some gals said they used to be worried that going to the gym would make them big and musclebound but now they thought getting big and musclebound would actually be pretty awesome, to Christine Love's Magical Maiden Madison (nsfw and basically the opposite of what I'm going for here, but part of the thought process anyway), to the kick-off of Bat For Lashes' "Glass" (wow that was a good concert), and to a bunch of other psychic grist that I'm forgetting right now.
(Working title: "Shinier and a Thousand Times Harder")