I'm gonna say, with a fairly high degree of confidence, that we'd need three months for a proper harem ending. I'll talk you through my thought process.
For a proper harem ending you need all the variant options for threesomes+a harem.
- Linda+Sara
- Caroline+Linda
- Sara+Caroline
- All 3 main girls
This can be extended further if you start bringing in other main characters such as Liza, Yazmin, Judy etc. (Or heck, why not Bob?)
To begin, you need to write an introductory scene for each of the possible variants outlined above.
Why would Sara want to share the main character with her sist- I mean, Caroline? She's an especially jealous character.
How would Caroline feel about you screwing Sara at the same time as you had been dating her?
There needs to be some kind of scene where the main character breaks the ice with both girls in order to propose a threeseome/foursome. The status of the relationship between each of the two girls has to be established.
There's probably some kind of intermediary scene then. A group date, a dinner, cinema, the beach - something where you can have all three characters talk and interact to explore their reactions to the proposed threesome, and see how they react to knowing the main character has been simultaneously dating both of them up to this point.
Finally, you can conclude each route with a threesome. You need to render a wide variety of images and variations for each scene, giving players the choice as to whcih girl they want to finish on, what they want the girls to do, lesbian options for the girls while MC watches.
And, while not necessary, a nice closing feature might be some post-threesome content where you could "summon" the women for threesomes at your request. Kind of like what you do when you wake the women up at night and pick from a menu of actions.
So, as a quick summary you've got:
1.) A lot of characterisation and script planning to do;
2.) Renders and animations for introduction, date, the actual threesome/harem, and post-game "summoning" scenes;
3.) A load of writing across these scenes to actually make a somewhat beliveable story that these women would suddenly agree to a threesome;
4.) Getting all this programmed.
I hope that clarifies my line of thinking; although, I am approaching this plan from the perspective of a writer, rather than that of a 3D artist or a programmer.
