I only have one real critique dev that I forgot to mention, and that is that the models could use more nipple definition. Right now it is like they are non-existent. With such huge breast you would expect some hot as hell nipple but right now they are just like flat. That would definitely need to be worked on in future versions. One last question is it possible to choose who you want to pursue a relationship with and still get a harem? Say for instance you only want the mother, Aunt Tina and Ruby, but maybe not the others. Will this be possible?
One last piece of advice I see that romance is one of the tags, possibly make it so that you can properly romance the female characters. I saw at the end that you considered min-games or events. These wouldn't be bad especially if the events help build up the relationships with them. What I mean is if you can cause there to be an emotional connection to the girls it would help the game be more successful in the long run. If the player feels emotionally invested in characters it usually increases the popularity of the game. So if you make it that the player feels that this is their relationship that they are building they would be more immersed in the game. That doesn't mean that you skip out on the lewd scenes. Not at all, but when there is that deep emotional connection between the characters it gives more of a deeper meaning to the lewd scenes as being something between people who actually care or love each other rather than random sex.
You already have a good starting foundation with the MC's mother with what he said to her about always being there for. Build on that where he either proves he will do that or just shows that emotional support to deepen the relationship. The same can be said for other female characters, where building that relationship will make for a better story.