I don't think this game will ever have a harem path, but I would love to hear your theory.
Thank you!
Now you’ve gone and done it.
Et tu, Brute?
Oh you're curious too and you know it.
So the obvious criteria is to have all main paths unlocked at ep 8. One must then choose Bella. If you choose anyone but Bella, she will back off. If you choose Sage or Josy and Maya you can't kiss Jill in ep 9. If you choose Jill or Josy and Maya, Sage won't try to kiss you in ep 11. You also get the best Halloween costumes on Bella's path: Mummy Bella and Bee Jill. This may be considered a hint.
But there is bound to be a bit more to it than that. I see the conditions for pulling off the MGH as quite elaborate. Simply because it would be the hidden path of a VN that branches massively. So not only must the Josy and Maya path be unlocked, it must be balanced at ep 8. You might even have to choose specific options for that perfect balance.
Since Jill's path must be unlocked you must go on the picnic with her instead of looking after Sage. This may indicate that you must friend-zone Sage until ep 7 as you can then not agree to look after her in the first place rather than choosing Jill over her. But there are so many things you get from the FWB route with Sage such as the HOT movie night. But more importantly the more heavily sexual relationship with Sage provides a contrast with Jill's heavily emotional one.
In order for the sharing to begin the girls must have a long talk about it and the really big elephant in the room will be why Bella. Jill's lack of physical intimacy should be paired with Sage's holding back on emotional attachment. The relationship with Bella is much more balanced between sex and emotion.
So why not Josy and Maya? Surely Bella can't be better than the two of them put together. (Well she is, it's Bella, but the story has to have an actual justification for this.) In this there would have to be some speculation on why MC made his choice. In my head the most plausible reasoning is that MC didn't believe the throuple would last and he would eventually have had to choose between Josy and Maya. And that would ultimately be worse because the one left out would have twice the heart break. But if he left both of them they would still have each other.
My head would also explain him not choosing Sage on the basis that he didn't think she saw him as more than a fuck buddy and no matter what she said about it, he had become the rebound guy. In this sense the FWB route is a better fit.
With Jill my head has to work a bit harder, but the explanation would be that while he doesn't say so in the bench scene he felt like Jill wasn't really in love with him and he was more like a stand in for her fantasy guy and as soon as he failed to live up to those fantasies the relationship was doomed.
Those are as said from my head and the game would have to confirm them. But I don't see the game as denying them at any point either, so they definitely could be added.
Another elephant the girls' discussion would have to address is are they all present or is there a sixth girl or perhaps even a seventh. To my mind the only potential addition would be Zoey, but perhaps not even she would be included. What my mind is undecided on is if the harem would have to be played as main girls only or if it should include some side girl scenes in S1-2. The girls wouldn't be members of the harem, but MC having those experiences would be a condition for the hidden path.
I can definitely see it that the game would demand a no side girls approach, but there is a great deal of potential in having a specific set of experiences. In general the explanation would be that those experiences show to MC the difference between love and lust. He knows what it's like to just have sex and so he knows that the five of them really are more than that to him. I will add here that he actually is in love with all five of them and a part of the previously mentioned reasons for not choosing one of the other three options was that he didn't believe they really felt the same way. To Sage he is just a fuck buddy, to Jill he is the stand in for the man of her dreams and ultimately Josy and Maya love each other more than him.
That was the general reasoning. More specifically it would be nice if MC had to be a bit involved in the intrigues, but not too much. Walking the line but not crossing it. From the meta gaming perspective it would mean making very specific choices throughout the game and thus activating the MGH would be harder to pull off.
For example you might have to accept the restaurant offer, but never buy anything. If you accept Jade's handjob she opens up about Stephen's cheating. You wouldn't be able to go further than that because the throuple would block it, but you shouldn't even if you could. You'd have to cheat at the midterms to be able to give Bella the information about how the cheating was done. Trying out the drugs but not fucking Quinn would go well with MC's misgivings on living up to Jill's dreams. And thus MC would have some info on all the intrigues which are significant to each MG path. The midterms cheating for Bella, the drugs for Jill, the Burkes divorce for Sage and the prostitution for Josy and Maya.
One other criteria might be that the wall must be complete. You must have won Hell Week, accepted the VIP pass and taken the fake ID. If you had to be as charming on Swyper as possible it would pair well with this. In order to chat with Nicole you have to get your dick signed, but having Jill's picnic picture blocks all the fun with her at the MILF bar. It also blocks Nora and the active throuple blocks Cathy. If you have to have the VIP pass and save Rusty's car the MGH would only be available with the mini-games enabled and I could definitely see DPC doing that. I just hope like hell meeting Madame isn't a requirement.
If you have to cheat at midterms the game would be Neutral by default as Jill's path wouldn't be unlocked otherwise. If this then paired with a demand to never choose the Neutral option in S3 and play S1-2 in a way that unlocks specific DIK and Chick choices it would add to the intricacy. It is quite probable that you have to fight Caleb and that would demand punching Oscar and more importantly Patrick. If the documents must be obtained Sage would have to join the Bailey's TG. If you on the other hand must be Chick with Vinny you can't have fought Tommy. Since you did the weed in ep 4 you must do the shrooms and Jill will disapprove when you visit Lana's grave, but since it's Bella's path you don't miss out on the campfire song and instead get Merbella.
And so on.
There are quite a few ways for the game to get intricate for this hidden path, but just about all of it could be justified by the story. Now would having the harem really demand all that? Perhaps not, but it would give the girls more motivation to share. The closer they are to each other the less they want to be the cause for each other's heart breaks and the more crucial MC is to them personally the less willing they are to step aside. And so the compromise of sharing becomes more appealing.
And they all bring something crucial to the table. If Jill's heart wasn't on the line Bella wouldn't consider sharing. If Sage wasn't there to suggest it the option would never be on the table. And if Josy and Maya never tried to share him Sage wouldn't get the inspiration to suggest it.