I have a few suggestions and I'll split them up into three, in reverse order of importance (the most important one is a bit of a wall of text).

3 - Gameplay suggestions
If you're going to put in gameplay for plot filler, please make it worth the time. Finding car keys and having to pick up garbage for 30 minutes straight really kills the mood. Using the Dark Dreams story as an example, I highly doubt the original story went "Then I went and picked up a piece of rolled up paper by one of the exercise machines and then carried it over to the garbage can." I would have much preferred spending that time with something relevant to the story, e.g Samantha making me fetch her things constantly and being a general bitch.
Here is a few specific gameplay changes I suggest:
- Using the exit door should take you to the world map, rather than having to go through the escape menu.
- Movement appears to be proportional to all components of the aim vector, instead of merely X and Y. This results in annoyingly slow movement when looking up or down. It would be a lot easier to move around if the movement speed were relatively constant.
- The game desperately needs a "Retry" option for sections of the story. It's annoying to have to go back a chapter because I was trying to unbutton a button and accidentally turned Tiffany's shirt into Cthulhu.
- If the player needs an object before I go out, the thought bubble should tell. "Maybe I should bring my camera to the photoshoot."
- There are many grammar and spelling mistakes throughout the dialogue. Running the dialogue through a spellcheck would go a long way. The inner Grammar Nazi in me apparently controls my penis because "Your'e" and "painfull" managed to kill the mood.
- Fast sex should be available from the start, and progressing through the story should unlock more content for fast sex. For example, you should start out with Latisha, then unlock Samantha, etc. and unlock more clothes for them as you progress, e.g unlock Jenna upon finishing the photoshoot, then unlock her dress by finishing the rest.
- The lowest limit for raising/lowering should be lower. I can't be the only one who tried to fuck Samantha after the sleeping pills only to be literally cock-blocked by a particularly inconvenient limit on lowering.
- The bodies are a bit too heavy. I can't be the only one who, after being cock-blocked by the limit of lowering on Samantha, was subsequently cock-blocked again by my character's incredibly weak arms and inability to prop her up on a couch or something. You'd think that if he was dragging her that slowly, someone would have noticed a fat guy stacking pizza boxes to get an unconscious girl into his trunk.
- The player-clip for the girls should be gone in fast sex mode, and the tables in the classroom should be draggable. Your imagination can figure out why.

2 - Clothing.
I think one of the things that makes this game ahead of the competition is the physics of clothing, and I highly suggest giving more clothing unlockable in the story mode. But, more than anything, I have quite an odd suggestion - Make the clothes less skimpy, and make more of them. I think it would be very sexy if Tiffany were wearing a set of panties rather than running around school commando, even if it has to be small if the engine can't handle multiple layers of clothing. Having the ability to remove clothing as physical objects means that we get to effectively undress them, and that's something that there should be more rather than less of. More clothes, more coverage, more fun.

1 - Face shape, skin textures
The body of the females are a great start, despite a few quirks such as blending issues for some poses such as Latisha's bed pose making her hips look like origami geese. However, I think the faces need some work, especially with Tiffany, Jenna, and Latisha. As far as shape goes, they're close, but no cigar - Jenna's mouth is mildly scary, Tiffany's face looks 15 which gives me the creeps, and Latisha is mildly terrifying, and the eyes on all the models seem overly large. I think XStoryPlayer should be diverging from the typical unrealistic hentai-like porn games that many people including myself have zero interest in, which I believe is what you guys are aiming for.
More important than the face shape is the texture. Jenna and Latisha both creep me out for the same reason - face texture. Tiffany and Samantha have enough detail on their face that I don't notice too much, but Jenna and Latisha literally invoke a fear response in my brain because they are literally creepy. The video "Why are things creepy?" by Vsauce on YouTube has a great explanation of why things are creepy, and this goes into that a bit. Jenna and Latisha appear inhuman and predator-like because their skin is porcelain-like, which makes it to where I cannot stand seeing their faces at all, as they genuinely disturb me. This leads into my final note.
As XStoryPlayer improves its textures and appearance, I highly suggest aiming towards a reasonable amount of realism and improving the detail on the textures, particularly with the faces. Someone might find a face with human features and the occ----nal (Apparently I can't say name of a specific brand of pianos for some reason) mole or imperfection unattractive, but it's much better to have a face that could be unattractive than it is to have a face that could be creepy. I can handle an unattractive face (e.g Tiffany), but a creepy face is a total turn-off for evolutionary reasons.

While I agree with most everything, I do strongly disagree with first (last?) point of arbitary stuff. The thing with doing useless stuff makes the actual sex something to look forward to. It is like sexy clothes (I mean like yoga pants and stuff that make sense, not that idiotic trend of calling a postage stamp sized piece of fabric a 'sexy dress') in suggesting that there is something worth waiting for later on. I would actually like to remove all the copy-paste-from-internet stuff from the walls and actually make the not-sex-stuff difficult. Or at least, if you do not do it right, you dont get any. There is plenty of instant-sex games that last for about the time of average masturbation.

I am perfectly fine with having things to make you have to work towards the fun, but what I'm suggesting here is that they be less tedious and irritating, and more relevant to the story.
For example, Samantha might have you pick up a bottle of water, then go get her tablet, then go get her shampoo, and so on and so forth, to give you the feeling that she's a nagging bitch.
The photo-shoot is an example of something like this working properly. The swimming is odd (is this some fetish nobody has told me about?).

If you guys (i.e developers) want, I'm sure someone on the forum, myself included, will be more than happy to run through the dialogue and make sure the sentences make sense and are at least reasonably grammatically correct. Then again, I'm a writer, so it's entirely possible that the grammar/spelling bothers me and nobody else, so there's that. :p