Art
-The art's nice but the highlight around the characters make them feel like they really don't belong in the scene, would make a good gimmick for dream sequences or imagined segments though. Or to highlight that a character is doing something really strange that you want to draw attention to, but for just standing around and talking it looks weird.
-Also the drooling face is a bit much for the scene it's used in, it'd work if the protag was completely spaced out, lost to his fantasies, but he's clearly concious of what he's doing, just keeping the blushing expression he already had but lowering the eyes would work better for showing that he's stunned/excited.
Writing (not a writer just some thoughts)
-Maybe try thinking about the logistics of the story first, like where is his harem supposed to come from?
-Random people he meets across the world, in just his home town, maybe merchants passing through or guild people that he meets, how is he going to start a relationship with these people he doesn't know and stay in contact with them long term?
-Will most or all of his harem be people he already knew? if so why wasn't he already in a relationship with these people? are they all family? this might be difficult to make work in a censored version. Example: the scene in the current build apparently MC is overcome with lust at the sight of his friend and she makes a remark that implies she wants to help him get his lust under control and he turns her down, if she were family okay, we can assume that incest is taboo in the game world that makes sense, but since he's not in the censored version it seems to happen for no reason other than that's what anime protags do, which uhm, that's done by anime protags do that to prevent adult ratings though, this is already adult rated MC is a hentai protag not an anime protag, we need a reason for his behavior, flimsy reasons can work fine so long as they're something that can be overcome in the long term so that the MC can eventually change/progress, but if he just behaves like that all the time for no reason MC is going to be hated). (As an h-game protag that doesn't belong in an h-game.)
-Have some roles/personalities/archetypes that play well off each other instead of just on their own planned for the rest of the cast since this is a harem game, and having characters get along with each other helps to sell that idea, that they're all in one big relationship not just being two-timed by the protag without their knowledge.
-Is there a reason the MC needs to be a japanese programmer? why not someone reincarnated from yet another fantasy world so his skills could have some utility? or will his programming ability secretly be a cheat ability(OP magic or reality warping since this is a game), why have him reincarnate as a baby if we're not going to meet him till he's twenty? why not use another means of transportation or even reincarnation? oh right forgot about the incest aspect for a bit... maybe make it so the mc's family got warped into another world while he was away studying and start the story with him having just managed to get into the other fantasy world? he could've gone with someone close enough to him to be willing to risk not being able to return(close friend/sister) to justify the girl at the start.
Random thoughts based around the isekai happening at the start
Could make it so the world they're from was anti-incest but this new world is pro-incest as a lazy excuse for him going from hesitant towards incest at the start to okay with it in public later on(could also be a reason for him to hesitate to return to his homeworld with his family, if he finds or knows a way to return everyone to their original world). Could also have time dilation between the two worlds just for some extra flavor or so the family members have had time to get over their inhibitions to incest by the time he gets there if you want them to be receptive to the idea right away, the overcoming of that hesitance is part of the appeal for some people so keep in mind this is a double edged sword narratively, it could also be taken as an opportunity to have him meet older versions of people he knew without having him purposely leave them for years if his goal all along was to remain in his original hometown, just have him learn medicine in his home town and while he's away getting supplies whether from a distant market or a lengthy harvesting expedition the family disappears. Maybe have them gain isekai powers(don't need to be combat powers) since they get summoned but you and the person that comes with you don't since you opened your own portal there.(Could have the summoner(s) summoning random people to try to find someone with a specific power and since your family didn't have it they got to roam freely, summoner(s) could also just be nobodies that accidentally summoned your family whilst trying to do something else like learn how to open portals for traversing their own world, meaning they'd have no clue how to send your family back home so their stayed).
-No need to make everything serious or about survival/combat this is an h-game after all (disclaimer: I'm not saying that taking the game in that direction would be bad just there's no need to force yourself to come up with that type of setting if it's difficult or not what you want to do).