I have some ideas though it might be too much to implement. (Sorry in advance if this is to wordy and hard to read)
1 a hub area that changes depending on if you save people or let them fuck until the animation ends with them fucked silly and wanting more. the more people saved will result in a hub area that's safer than before (as the hub is overrun with lust crazed people that will attack you) and not as many people fucking (thought there are still some fucking in the background).
shopkeepers will be decent and will sell upgrades that will increase the time it takes for the enemy to rip your clothes of and fuck you, halving the energy cost for special attacks to even an increase to your damage.
the other route however will result in an equally safer hub, but it will be littered with people fucking everywhere some buildings will be renovated into a lewd version of what it was ( i'e a hotel be more of a brothel the anything else) some of these can be interacted for a free'ish (if the pregnancy mod is not enabled) sex scenes.
shopkeepers will be nude and or fucking, be cum covered or pregnant (it can even be all at once if you're lucky). they will also sell you upgrades that decrease the damage of sex scenes, allowing the qte to persist even without clothes (I'll get to that soon) to allow the player to fuck downed enemies for extra money.
2 degrading decency. as you get fucked by enemies and characters the player will slowly be more open to sex and being naked/wearing lewd outfits (note that all the scenes is for the hub and some scenes in levels but not the enemies)
here is some examples (dev might want to change the threshold if this is implemented)
0-24 the player will not partake in any sex nor love being fucked and will not like being nude and if they are nude damage and movement are decreased and damage dealt to the player is increased.
25-49 the player will partake in handjobs, titfuck, thighjob, hotdogging, footjob (both giving and receiving) and even slightly start masturbating before quickly stopping themselves, wait animation will be the same, they will still refuse to be nude, yet they will accept slightly lewd costumes (being nude won't be as dangerous as the previous threshold but still something to be mindful of).
50-74 here the player will partake in blowjobs, (both giving and receiving), light stripclub (mostly dancing), light prostitution and the player will masturbate to a climax now. waiting now show the character you're playing as sometimes play with themselves or a once normal animation now slightly lewd. the player can now be nude freely no without any debuffs and can were even more lewd outfits.
75-99 the big one the player will now engage in all manner of sex, a lewder strip club event (public masturbation), lewder prostitution, the player will masturbate to a far more vigorous orgasm and waiting will start daydreaming and actively flash you.
100 orgys, public sex (both on the street and in the strip club), sometimes masturbating a second time after the first orgasm, waiting will result in the player beckoning while flashing and or playing with themselves and outfits will be more fetish than cloths. this also open a secret ending if you didn't destroy or open them yet.
3 endings there are some variables that are accounted for the ending you're going for.
destroying Venus's pod filled with more love potion (good), fully opening it (evil) or modify the love potion and opening it slightly (sex fiend/lewd neutral)
the chaos emeralds this will lead to the true ending of each route.
the degraded decency this is more of a change in how the endings go from 0-24 (pure) to 100 (sex addict)
the ending (you just need to do one of each route to earn your reward except the ending pics) are also come with their own rewards and post-game.
good gives you the heroes that are fighting against Venus, a post-game levels that are remnants of Venus, and a much tame (though the effect of the love potion isn't gone yet) world.
neutral gives you characters (like the captives and shopkeepers), levels that consist of locating and stopping Venus once and for all and a world still under the effects of the love potion.
evil unlocks all the characters (bosses and no captives that you find fucking) level where you attack people no effected by the love potion, a world reeking of sex and pools of cum and an evil mode that let you start at the final boss location and work through the levels but instead of the enemies fucking you they will attack you like you did in the base game but you start the grab and fuck.
sex fiend unlocks genderbend mode, level consisting of you finding more people to fuck and a world in between the good and evil route.
4 pics scattered around the world will be pictures many will only appear in one of the 4 endings, and some are only acquired for beat an ending as a character (unlocks, evil mode, and genderbend mode, included)
5 genderbend mode self-explanatory swaps gender of everyone
that is all i can think of atm I know some if not all of what i wrote will be implemented and i fine with that as this was just me writing my thoughts for everyone to read who know maybe someone will make their own version of project x with some of my ideas in mind.
again, I'm sorry of the wordy and no doubt a pain in the ass to read post note that this was written with a 2–3-hour worth of sleep.