Sounds to me like you don't want a GAME, you want a movie/char creator.
You are delving into the concept of what a game even is. For me, it boils down to simply, "an activity that one engages in for amusement or fun". Spending countless hours building a character, choosing the perfect scenery, position, camera angle, to enjoy smexy action falls well within that definition.
A movie/char creator can be just as in-depth and complex as a traditional game can be. Again, take Koikatsu for example, the character creator itself is amazingly complex (especially with the help of mods), able to closely recreate majority of humanoid characters. Just browse Kenzato, the variety of characters the community has managed to create and share is astonishing.
The sex scenes themselves can contain a good amount of tinker-able settings to get it just right for your taste (something traditional video porn can never hope to achieve). All the way from simple camera view change (POV or third person) to how much the characters spine should bend (with the help of mods in Koikatsu). Recently
TrueFacials's update showed more can be done instead of just a simple speed control when thrusting, he added thrust weight, start depth, end depth, on top of speed to give more variety and control to the basic thrusting movement. This makes it
much more satisfying than video porn.
A good movie/char creator is a massive endeavor and no simple task. Again, I don't mind if Derelict works on the story/gameplay portion. But I find traditional games in that sense has been done to death. There's so many indie and triple A titles out there it's difficult to compete with them. Whereas a good sex simulator is rather scarce on the western side. It's nice to see the western audience slowly warm up to the idea, play catch up with the Japanese in this genre, and perhaps eventually surpass them in their own game.
Personally, I see
massive potential in the creature creator in BotN. The variety the current build can create is already amazing and sexy af. I'd love to see what more he could add to further increase the variety. The sex scene part however is quite lacking and something I'd like to see improved.
Apologies for the long write up, I just truly want this game to succeed, focusing on the movie/char creator aspect is something that could work to bring in more audience and funding given the rarity of a good western sex sim.