Possibly one of the tiny but very cool details of Bannerfall that I think add to the characters and story as a whole is how everyone could've just left at any time if they wanted to.
In the other POW SMPs that I've watched (Cowboy & Vampires) there was something keeping the characters within the borders of the place where they were, a literal wall keeping them trapped, making the collective goal to get rid of the wall and leave. It's true that not everyone necessarily wanted to leave/left (especially in cbsmp where a lot chose to stay in Pity, because those that stayed in Oakhurst didn't necessarily plan to stay there at least at first while in cbsmp some just were residents of Pity) but in general, getting rid of that border keeping everyone trapped was a bit of a collective goal of everyone, whether they left at the end or didn't.
But in Bannerfall there was no border or anything keeping everyone there, especially made clear by the fact that they had guests come over from time to time, but also that some characters did canonically leave for a while and then come back. Along with it allowing for things like cameos to happen, it also showed one of the characters' motives. Because when you can leave at any time, staying, especially in a place with active warfare like the kingdoms, is a conscious choice.
Literally everyone the second they realised the monarchs were dead could've just left and ended it there, but they chose to stay.
4C chose to remain in Bannerfall after Nom hit him with the mace. I'm sure there were others that too could've just left if they wanted to, and maybe they wanted to even just a little bit and chose not to. Even Nom, when at towards the end said that if he survived he wanted to leave, could've just left at that moment if he wanted to; nothing stopped him from doing that, even with the Creaking King's curse he wasn't bound to the place itself. He chose to stay because he had a reasoning to stay, he had something to fight, people to protect. Every character in one way or another could've abandoned Bannerfall once and for all and didn't because of reasons different for each one of them, because they didn't really have any common goal that kept them there apart of, later on, defeating the Creaking King. This adds so much to the characters, a personal motive that is unique to everyone and motivates them not to leave until they have finished doing what they came there for, what they're working towards.
In Vampires, most characters' goal, at the end, was just to leave. Apo wanted to go back to Cherri, Scott wanted to travel the world, Abolish wanted to go back to his family and friends, and so on; the only two that stayed in Oakhurst when all was done stayed merely because they had nowhere else to go and they were familiar with the place, everyone else left, in one way or another.
In Bannerfall, those that left at the end had a reasoning that made them leave, but that wasn't necessarily a permanent leaving either. Apo and Cherri went back to their actual kingdom, Scott and Mae chose to sail in Nom's honour, Graecie went back to the Grotto to heal the horses, but everyone could and some would come back later on, they had some sort of attachment to the place that was not caused by being forced to stay, but by finding a reason to stay. And for some, the reason to stay is still there, and they never left.
Some even have a reason to return. At the end, those that left have people they care about that stayed, and they probably went back there from time to time. At the end, Bannerfall to them was more than the place they were in for a bit of time that caused both good and bad things. Few went back there just to mourn, most came back to visit people, to see how the kingdoms are doing, just to reminisce the months spent there, with friends and foes alike, a chapter of their life that is ended and closed but they can still look back at.
Differently from VSMP or CBSMP, the way the characters in BFSMP experience their time in the kingdoms is similar to ours, as the viewers. Because like us, they went there not knowing what was going to happen, and chose to stay until the end. And when the end came, some stayed with it, some left, either immediately or after a while, but even those that left will remember the experience, and maybe go back in the future. And I think that's beautiful.
Bannerfall was an amazing experience. Like all roleplayed SMPs, it feels so alive, so real, that one can't help but feel actual emotions towards the characters, the same way the characters feel real emotions towards each other. It was wonderful, something that I'm sure I'm not the only one that enjoys looking back to.