Do you know these games? You can have (a few) hybrids in them. And most likely the art and animation style presented in these games are the only viable option if you want so much variety.
https://f95zone.to/threads/overtopia-origin-v0-9-8-5-1-1-silvergogs.4783/
https://f95zone.to/threads/overtopia-b-w-v0-0-11-silvergogs.4787/
But, I think you guys should stop. Honestly, you are talking about neoteny and ferals and face variations and hybrids and on and on and on... Let me ask you one simple question that has already been answered a hundred times in the BS threads. Why was it impossible for them to ever finish that game?
About creating the game... I think that we should try to gather people to do it, because otherwise it will not fulfill certain minimums that people needs to like things.
If you start writing a game design, and I start doing the same thing it's not very efficient. I understand you completely, in university I LOVE to work alone, but that's because it's easier in those things, but for this it would be impossible I think...
About why BS failed, I don't think it was because of the animation combinations at all, I heard they had persona problems and that made them stop.
I don't think it's impossible if you make things with references, if the base is good. Look at "Super Deepthroat Game", okay, in that game, the combinations are... how many? 10^100? 10^1000? But they work all perfectly. They change height, inclination, genital size, skin colour, they paste clothes and skins, hairstyles... Many games are way bigger and have much more combinations and they work, it's all about the base, if you have to create one animation for each, then yes, if you create a base and then paste characteristics on it, then it's different.
And that's an OLD game MORE THAN 10 YEARS OLD, probably older than BS. And you will tell me: "But the whole game is about that" Yeah, but that is a game to simulate sex, what we should have to do is WAAAAY more simple, since what we want is that the player doesn't have to control the sex actions, he just watches the animation, and the game pastes the monster's traits "Height, cock size, colours..."
Really, play "Super Deepthroat Game" and you will see what I mean, how it changes when variables change, but we just would need to do much simpler art. Not super detailed like that.
https://f95zone.to/threads/super-deepthroat-v5-41a-konashion.4605/