In Alive, if you would make the game to be in Mary's POV instead of the current MC, what would change in their interactions and why? (and I chose Mary here, because she is infatuated with MC at the beginning of the game while MC hasn't had a thought of pursuing her)
I have no idea. That is way too complex a question to ask without a really long and dedicated answer - the entire dynamic of the game chances, because you're trying to put the player in the shoes of a totally different character, and that requires changes for the sake of gameplay.
But let's take this another way and say "What happens if you change the POV, without changing the story" - in which case, pretty much nothing. In that case, you're simply forcing the player to act a certain way rather than giving them decisions. But what about the MC? Before he was making decisions, so what is he doing now? Well, as a dev and a storyteller you have to decide which way you want that person to act, in my case he'd reject her because I have an idea of what I personally consider the "Canon route", and Mary isn't it. I mean sure you could make the npc "decisions" rng, but I personally fucking hate that idea - and since decisions need to be made one way or another, and it's weird to have the player make decisions for the NPC, you'll have to force it, soo..... Yea. Doing something like what you suggested would require such a massive overhaul and re-write of the entire story that I don't think it's a fair question.
And going back to the "beach or mountain" question. If Alive had been in the POV of Nikki, by the same logic you pose above, she would answer "great, me too!" regardless of which answer MC chooses. Yet, when in the current MC POV, she doesn't. Why is this?
No, by the logic I propose this wouldn't happen at all. If it was in the POV of Nikki, what would happen is the MC would pose the question (as he did originally), and then instead of her just answering "beach!" the player would get the choice - because that's what a lot of these games are about, player agency. When you're talking about swapping the POV, you're also swapping the player agency, which can change how things play out.
When I write everything, I have a "canon" story (which means choices/decisions/etc) in mind, but I'm still giving options for the sake of player agency.
In fact, I'll tell you right now: In the "canon" version of my story, MC prefers mountains, Nikki prefers beaches, MC isn't into mary despite how she feels, but despite the beach/mountain thing, everything else MC does is something Nikki likes, and the Ch4 date scene is with her, and not with anyone else - that's my "canon" version. If I'm being honest, I actually sometimes don't write quite as much for that version of the story, because it's the one that I consider the "natural" route, and so I end up putting more effort into the other paths, since they aren't the ones I initially envisioned.
So for me at least, when you're talking about swapping POV, everything still plays out via the "canon" version, but swapping player agency to whoever the new MC is - and in that case, the story may end up changing drastically depending on the options the player makes - and the (current MC), would now no longer be given options, but rather act according to his "canon".
The problem with basic point system is that you only get two paths: pursue or not pursue. The only dynamic is when MC gets off the pursue path. In contrast we can take Dog Days of Summer, where most choices are story branching points to some degree. This makes the game pretty complex to manage, but dev does mostly by trying to merge branches whenever possible. That game is the best there is in terms of story dynamics in my opinion.
I haven't played that game so I can't speak of it. But I can say, no matter how complex a system looks, if you break it down far enough, it always boils down to binary choices. You can always be clever and layer and stack these, which can get incredibly complex very fast, but binary choices is always what you'll end up with at the very base level.
Since you asked about my game previously, I'll use it as an example.
We'll take Mary. There are currently 3 viable paths regarding mary: (actually 5 but I won't talk about the 4th atm). Path 1: Reject her. You don't pursue Mary, she remains mostly a side character in the game.
Path 2: Pursue her - you pursue mary, and I haven't finished the game yet so I'll just say "We'll see how that goes."
Path 3: Sort of Pursue her - there's a path available where you can pursue mary, but NOT go on a date with her, but still leave things open for later if you wish. It's actually a bit of a PITA to even get on that path since it requires some careful navigation, but it's there.
Path 4: We won't talk about this.
Path 5: Pursue her, then reject her. Stacey comes a-knockin'. This one exists, but obviously isn't really considered "Viable".
That's 5 possible paths with one person - but it all always breaks down to binary choices. Pursue or don't - but path 3 involves another couple of binary choices on top of that.(Technically path 3 involves a choice that isn't binary, you have 3 options and only 1 of the 3 leads to this path, the other 2 take you in different directions, so I guess most of my argument falls apart here, but whatever) And so does path 4. and so does path 5. And the interactions, and the way people may respond, or act, will differ depending, but it's always due to a series of binary choices.
For example, the stuff I'm currently working on is a scene with erin and nikki alone (No MC, just the 2 of them) - and I created 3 different versions of that scene, depending on how the end of the last chapter played out - and it's not just minor dialogue changes, but the scene is vastly different depending on what happened the night before - but it's still all the outcome of a series of binary choices, which lead to one 3 possible scenes playing out.
Maybe this is an inability for me to see things beyond my own perspective, but I can not envision ANY sort of system that, at it's core, doesn't boil down to binary choices.