This felt more like an engine for part of a game than a game itself, which essentially it is; however, I found it surprisingly addictive and probably spent more time playing it than I should have.
As for feedback, a few things came to mind: In general, I'm not a fan of the popular tags mechanic for videos. More specifically, sometimes you get some pretty banal ones such as TitRub, Kiss, TitLick. Maybe categorize them into discrete lists such penetrative acts, breast acts, and others or just penetrative acts and others, and then have each tag be drawn from a different list or two from one and the third from the other. It seems that only the first action you pick counts toward the tag which is probably the better choice in hindsight, since it'd be very annoying to keep track of all sex performed otherwise, but isn't necessarily intuitive. Only the first sex act counts towards satisfying a girl's request during sex. That is frustrating both when you have two girls both making requests that aren't mutually exclusive, and when you have one demanding girl and are trying to meet the weekly tags. Demanding girls are too demanding. If I'm getting it right, there are four levels of demanding. They either make a request every turn, every other turn, every three turns, or never. At the highest level, it is impossible to both meet the weekly tag and satisfy the girl. Maybe back it off a step to every other turn, every three turns, every four turns and never. It would still make it almost impossible with two demanding girls but the player should know better than to pair two highly demanding girls together after the first time.
As for non-tag related feedback, sex skills probably increase too quick. The MC goes from virgin to sex god in under a month. Stamina drain probably needs to be cut a bit. Even at sex-god level, the number of turns MC lasts that I've experienced is between 12 and 22 depending on RNG with 13 being uncommon, 14 being somewhat common, and 15 being most common and the 22 being a one-time fluke. I do think 15 is a good goal to keep it from getting too repetitive and boring, but by the time the MC reaches max level in all skills, failing to reach 15 turns should be fairly rare; he's basically a professional at that point. Also, there appears to be a mechanic to spend stamina to gain energy, but I have never run out of energy before stamina.
The RNG on a girl's satisfaction and arousal doesn't always make sense. I've been praised for correctly guessing a girl's favorite action, performed it at the perfect speed, had the other girl in the threesome go down on the first, and it still says the first girl was disappointed by the turn. In a threesome, acts the girls perform on each other should count towards improving contentment and arousal; it currently doesn't seem to. While it seems mostly related to the snugness of an orifice and the size of the MC, with largest being the default, there is no benefit selecting any speed other than slow. You might take a small hit once a girl reaches wide, but there isn't any incentive to select a different speed due to energy conservation. It makes sense that more physically demanding actions would take more energy, though. I have never seen a girl prefer hard, again probably because I'm playing with default penis size. While I don't have a practical suggestion, a tweak to make other speeds viable would be nice.
Lust gain probably needs small tweaking. I've had girls go from 75 or lower to masturbating, usually from hearing sounds or acting as a cameraman. They should cap at 100 and give you a turn before masturbating. Perhaps have a holding period at 100 based on libido with high libido girls masturbating the turn after they reach 100 and lower libido girls waiting. On the other hand, masturbating is one of the ways girls lose stress early to mid-game, so that would really punish low libido girls. Anyway, something to think about. When a girl masturbates, her lust goes down to zero at the start of the next turn. When the MC satisfies a girl, it goes down this turn, but she gains lust at the start of the next turn. I kind of feel like that should be reversed. If you make a girl squirt, she should be at zero the start of the next turn without any gain while the girl that masturbated should still have some lust.
The jealous mechanic can be brutal. I've lost 25 or 30 opinion just from talking to someone, and I've had all the girls in a household be that jealous. It really is too RNG based. If you're lucky with the girls' stats, getting a harem with all the girls is possible with patience. If you're unlucky, it's impossible. Now, part of the fun of a game is the challenge therefore it shouldn't necessarily be easy, but it should always be possible. Maybe have the RNG for those stats be generated on a bell curve limiting the extremes. It is similar with sexual preferences; I've seen strange ones like girls who love and like handjobs and activities involving their breasts while avoiding, disliking, and being ok with everything else. It also seems the average skews towards the lower end with dislike and avoid being more common than like and love. Let's be honest: this is a porn game; the average should skew the other way. At the very least, let them slide one or two spots. If the action is used enough to qualify as a tag in an encounter where a girl squirts, she'll be more favorable towards it. If used in an encounter where she is unsatisfied, she'll be less favorable to it. If she orgasms but doesn't squirt, it remains the same. If not used for a while such as two weeks or a month, it moves towards the default. Make it like the snugness stats although that seems to revert weekly. A girl with a natural avoid preference can have it rise to okay. A girl with an okay preference can have it range from avoid to love. A girl with a love preference can have it fall to okay. Maybe have a maximum slide of one from one-on-one encounters and a slide of two possible with threesomes. Humans are social and competitive. If a girl sees another girl enjoying anal or getting a facial, it will become more acceptable to her. We could probably do the same thing with orientation. With such a system, you wouldn't even have to do anything with the low preference bias since everything would be somewhat fluid. Maybe also break the preferences into two lists so that the less universally enjoyed skew lower and the more universally enjoyed things skew higher. Still, I don't think RNG generated stats work the best here. It might be better to do templates. Have a template with nine characters or three characters in a household whose scores are balanced against each other. Those character scores can then be randomly distributed among the various characters, maybe with the girlfriend being fixed. There can be multiple templates for additional replayablitly. It would prevent the RNG gods from generating a set of stats for the characters that make advancing exceedingly difficult or an overly curious set of sexual preferences.
A relatively minor quibble, but some of the secondary actions in threesomes raise eyebrows. For example, you give do a titfuck or titjob with one girl while sucking on the second's breasts, the second might choice to eat out the first which, while not impossible, would take a lot of contortion and likely impede the breast-related activities. A second example is during cowgirl if you perform oral on the second girl. If the first girl either kisses or performs a blowjob, it can end in a double blowjob, which would require one girl to get off and turn around. This kind of feels like an minor extra turn which doesn't fit with the rest. Still, it's just a minor quibble. Also, while on the topic of minor suggestions, make multiple squirts possible. Sometimes, the RNG gods smile upon you and you get the girl or girls to squirt fairly quickly. You are then left completing turns because you are trying to raise a girl's skills or reach the 15 turn mark for a video. Having a possible repeat performance by the girl would make it more interesting.
I understand this is basically a tech demo, but here are some things to consider for the future. More sexual positions might be nice. The current selection works well, and too much bloat would be bad, but maybe including options like spooning and a distinction between cowgirl and reverse cowgirl. Maybe making positions more fundamental to the system and rethinking what can and cannot be done in certain positions. For example, you probably should be able to kiss a girl in doggy or rub her pussy, or finger her ass. Having a anal or a two-in-the-pink, one-in-the-stink fingering option. Having the difference between vaginal and anal sex in each position like with cowgirl and anal ride. Have the ability to do anal ride without cowgirl first. As I mentioned, I did find the gameplay surprisingly addictive. I also have no idea of the coding. What I am envisioning as minor tweaks might be a coding nightmare that isn't worth it. I'm not even sure if I'm describing this well.
If you are making enough money, have a possibility for people to quit their jobs and do porn full time, giving a second turn both for the MC and the girl involved. This would also allow the MILF-characters to have more energy at the start of sex which might be a bit of a curse with a demanding MILF. Also, if the MC quit and could do two scenes a day, it would probably require of rework of the energy system, so limiting it to the elder sisters and mothers and keeping the one-turn system might be best.
An ability to record multiple scenes a day. Once you have multiple girls signed on, maybe you can also do a lesbian scene. You'd probably have to invest in equipment again to set up a second room as a studio. You can then pick two of the more Sapphic girls to record a lesbian scene. Have an option for a cameraman and maybe a director. It wouldn't need to play out like the normal sex scenes. Just have a score generated on stats. Play a couple of video clips with a text summary of how successful the scene was as a review screen. Maybe have addition talk levels. You'll have to talk to girls before they agree to lesbian scenes; you'll have to talk to girls to get them to direct. Based on stats, some girls might be better directors than others. That would allow more girls to be involved a turn, and would give the player more control over the girls' lust levels moving into the late game. Similarly, foursome and moresomes. It would probably be a nightmare to code and not worth it, but being able to cap off a successful harem run with an orgy would be great.
Wow, that got away from me. I came here thinking I'd write two or three things, and it turned into a novel. Anyway, thanks for the surprisingly addictive tech demo; it really captured my imagination for some reason. I would love for the sex scenes in more games to have a mechanic even somewhat similar to this. Good luck in your future projects.
Edit: It would also be nice if you could have a quick chat with a girl or give her money without it using the entire turn. There are times where you've progressed talk as far as you can, and you haven't and can't seduce a girl yet, which just leaves the option to end turn. At the very least, make working part-time still be an option. Also, if the flexible preferences idea were implemented, it should also affect cameramen.