I finished the game. Here are some suggestions.
1- If you are going to make me grind, make the game optimal to grind. Add a "quick breed" button for each character in the cave and for the three girls from the household. Also you may improve the shops because when I want to buy something, like Biomatter in the hardware store, i have to scroll down to buy again, making it super tedious since you need a lot of it. Perhaps adding the option to buy more than only 50 each time will improve it.
2-Consider adding a "easy mode" that lowers the price of the upgrades  or makes it easier to gather resources. After all this is a porn game.
3-Add the breeding event of the three households girls, where they get pregnant by your thralls, for the girls in the cave too. 
4-Maybe add Kelsi Monroe, great actress that also got pregnant at some point of her career.