Realize that I'm late to the party. VERY late, but I'd like to throw my two cents in for ideas. I'd like more content on the cum witches from the first game. More specifically, I would like to see features that allow the player to become one and have magic based around lust and their cum. Lust could control how powerful the spells you cast are and cum would act as a sort of mana system, i.e., the more lust you have, the higher tier spells you can cast and the more cum you have, the more often you can cast spells. To expand on this, I would very much like to see more content based around docking. A really perverted way of easily replenishing spent cum after a battle would be to dock with an enemy, assuming they have a penis and the player's penis can fit them, and steal all of their cum through a forced orgasm.
I imagine this would be very time-consuming and hard to implement, considering previous and future npc's would have to be re-written to have a docking scene, and the magic system may need extensive modification to play nice with the cum witch features, so I won't be disappointed if this never gets implemented.