Ok, my lousy attempt at an impromptu "guide"... ha ha har har. Guide, right. More like random pieces of information that will hopefully help various people.
When you have sex with many of the girls (especially with significant energy in the white bar) there's a chance of them dropping a present box. Picking them up places various "contracts" that, once unlocked, you can equip to your male or female forms. To unlock them you will need to buy or find a small peice of paper that almost looks like a diploma. It is beige, with brown border and lettering. It costs about 50 in the store if it spawns, and I believe spawns naturally after the slime boss. Do -not- think you can just ignore this part of the game. While yes there are contracts for every type of girl and most of them don't make sense there are two in particular that are crazy useful. One is downright required to beat a later boss. They are the fire girl contract, and a harpy contract. You can equip two contracts to each of your forms by going into your q menu, second column, second option from top. Each portrait will have two little squares beneath them. Select, and equip. Some contracts have limited use, shown numerically. For the required fire girl use see the ice legion boss below. The harpy will stabilize the otherwise erratic and uncontrollable movements of one of your later forms. You'll know, when she bounces off of things like a pachinko ball when running around. It's not as cool/fun as it sounds. Especially when (spoiler) you're forced to use her and can't revert between forms.
Also, once you get an item which I only noticed it long after I had apparently gotten so I have no idea where it comes from, you can masturbate. Down-Z. This can hurt you, but mostly looks fun and has some odd uses I'll point out. Such as a witch girl who will chase you around and aggressively keep giving you footjobs until you're spent. However if you start to masturbate she'll decide she'd rather watch, and if you pop her she'll leave you be. Also, of all the statues within the game there's one in particular in the green/2nd area of the game which if you find and blow your load on a few times will trigger an optional boss fight (make sure your white bar is full enough for this). Also, if you masturbate during the fight, the optional boss would rather interrupt and give you a blowjob rather than whooping you with a bigass scythe [there is references to mindcontrol going on, the mindcontrol is to kill you, and you may be overriding the mind control with lust and getting blowjobs instead]. If your white bar is full (and there is a spa in the room to recover that), the more she swallows the more of her health will get converted to yellow. You can win, without actually fighting her.
By the way, you have a hotbar that starts with 3 slots, and can hold more using weird voodoo I haven't figured out. As a female you can press s to cycle between them without penalty. The option to access this is either the first or second option on the first column of the q menu. It's good to familiarize yourself with this because cutscenes that have you switching forms for various purposes can accidentally override your hotbar selections and you'll have to reconfigure it.
See those pink doors? Don't waste time trying to figure out how to open them for most the game. Near the end you will be forced to navigate a bunch of areas without being able to switch to your female form. You will be given a special pink skeleton key (which you will have to backtrack 'just one more time' to hang out with an npc in order to get. It'll make more sense when you get there) that will open them all. They reveal shortcuts or special red/blue orbs that change level mechanics that are designed to go through as just the boy. You're not missing anything for the entire first 4/5ths of the game.
Progression is confusing, and my dyslexia is a little too bad to give specifics but I will try to give some advice. There are doors and stairs which you can press down to go through. Quite a bit later you will be in a stomach like area (no vore, don't worry about that if its not your thing) with crack like decorations. Those are actually doors. They are complicated in how they hook-up but a little experimentation and good mental notes as to what does what will get you through. Once you've entered the castle proper you will be in a "purple" area. Next comes a "green" area. You can get another form in this general part of the game through dying to a hopeless boss battle and getting turned into a statue [this girl can powerslide through openings 1 block tall). In another part (made obvious by green kappa girls first appearing - I think, either way, its a new subset of the green area) there will be a large box like design in the lower right corner of an otherwise empty aside from platforms, gigantic room. Navigate your way through and you'll find Ms. Pachinko-nut (the first form who can jump through 1 block openings). No, you probably won't have a harpy feather yet. Also, if you come across a gray block room with GIGANTIC metal doors blocking your path, remember how you got there. This is the "library" and you'll be back quite a bit later. Back-track a little, and with a bit of exploring you should find yourself at the very bottom of one of the earlier sections of the green area (it's actually a completely separate set of tunnels within the section that you have to access from a different screen transition) that goes out through the bottom of the section. Keep working more or less down and to the left and you should eventually reach two waterfalls - hopefully... if you're on the right track. Ms. Pachinko-nut fires icicles that can freeze sections of the waterfall to let you jump up and make your way into a dark-purple/red section. Here you will find harpies, and they are difficult. Good luck.
You will also find the "ice legion" boss, also known as "giant multi-orgasmic snow girl orgy ball" or some other such variations. This is one of the first bosses that actually has a sex animation (that I know of). The reason why this boss wreaks so much havoc is the health regen rate. Perhaps there is some special mechanic to "lock out" part of the health bar so it can't respawn (which you have to do for later bosses) but nobody's figured it out. Take the first female form you get, equip two fire girls to her using the above mentioned contracts, position yourself on the blocks on the left side of the stage so you don't have to jump to fire at the boss, and make like anti-aircraft fire. The two fire girls will fire in-synch to your shots.
After the ice legion, head... right.. ish. You will probably have noticed that directions are not quite so easy and include a bunch of zig-zagging and finding hidden screen transitions. You will enter into the stomach area. There is a boss to fight in here, which has absolutely no relevance that I can understand. Optional maybe? Anyway, keep looking around and use the cracks and you'll eventually trigger a cutscene involving a green haired, mostly nude girl, with a red shawl. Follow her out into a large open area and after some lengthy conversation she'll give you a mystery item. My guess is she's asking you to get a book for her from the library, that place I mentioned earlier, and she gives you the key to get in. The place is a pain to navigate, but its a bit of breather with the opponents. The sex scenes here are generally the more difficult ones to find. The harmless girls floating around have to be approached by one of your female forms rather than the male form, and the fox girl has to be aggro'ed first. Somehow, (she didn't do this the first time I was through, only on later visits) will attempt to dodge your attacks. If she successfully dodges she may fire a purple stasis orb which if you get hit by will hold you in place and slowly leech your MP. She will drift back and forth a few times. If you either breakfree or revert to male form (something along those lines) while she's passing over you, the two of you will get trapped together and you get the scene. You have to do this because she panics and flees if she's not trapped and sees your male form.
The book in the library is yellow, shouldn't be too hard to find. The place seems like a maze but its not much more different then the minotaur's labryinth. Just keep working your way through. Return the book to the girl in the open area past the stomach region (yes this is some really irritating back-tracking here). I forget how many conversations you have to trigger, just bear that in mind. Eventually she'll manage to use the book to blow herself up. This doesn't settle well with the evil presence in the castle who will rez her, then mind-control her into attacking you. For the duration of the fight, you will have the yellow book which will give you the option to crouch and press x in any form to create a shield around you. If you get hit during this fight, you will lose the book and if you can't pick it up before she does she'll blow herself away again. Which triggers the evil thing to rez her back to full health. However, if you pick up the book after she blows herself apart, take out the gaurdian red orbs around the blue orb (evil thingy, thing, McThing) and use your shield around the girl after her rez, but before her health restoration you will lock out a portion of her health bar. This can be repeated, locking out more and more of her health until you either win by default, or just have that easy of a time blasting her.
If I remember, you get to cross into a water area now. There will be a point where you're supposed to drown, make sure you've got no other linear progression options first. You'll get something that lets your male form move quickly underwater, but not your female forms. My game appears to be -slightly- more bugged then other people's, and if you're getting mad sexings underwater when your breath runs out, you won't drown and will instead get unlimited underwater exploration. This only works for the special water in this area, such as the water that changes heights. It doesn't work for the green springs or opaque blue water elsewhere. Beware gigantic mermaid orgies if you're doing this. They can be a little difficult to escape from. They are also extremely awesome.
Now, at this point I had been awake for a really long time and I can't really member what happens after this. The next areas are somewhat off of the library and some sort of tower like structure above it. You will eventually find and release the magic girl who's form you've been using from her crystalline slumber, and start the section where you're restricted to the male form. Just plod along, meet an old boss who's now friendly, aimlessly drift around talking randomly, see a few cutscenes, get the pink key to open the pink doors, and then you're tasking with making your way to where you originally got Ms. Pachinko-nut. Using the pink doors it is possible. You will be forced to sleep in one of the inn-like rooms on your way, keep that in mind. It's right before the gigantic tower of spider blowjobs.
Once you regain that form, I am stumped as what to do next. I can't find the next area (and possibly final area to the game). So the little stuff I know runs out here.
