So, anyone who has been adjacent to my dm'ing knows I have a soft spot for Pathfinder 2nd Edition. Moreso than its direct competition, PF2e is clearly modular. Classes only have a handful of hard features with everything else being a choice from a pool of feats, which allows for a strong level of "build your own character" without being so open ended that the process becomes entirely amorphous. It's this high depth with modest complexity that really opens things up. Any TTRPG veteran could think up of the Level 0 character variant rule on their own after looking at where and how each value on a character was assigned, which in fact happened with me when I did my first PF2e campaign and is part of the reason I'm writing this thread.
In my first PF2e campaign, my second campaign ever as game master, I had my players play their characters before they had become heroes.
The idea behind a player character with a level in a class is that is the first step into the realm of being a heroic entity and it's what comes before that that heavily drew my interest. From the first time I had ever played a game of D&D, I wanted to make my character so that it fit into the world of the DM. Sadly, my first time around I had a very immature DM who didn't have the experience to understand the curiosities and interests I was too inexperienced to describe properly. Even after moving on to playing with Melonmancy and playing in a more understanding environment, the attitude was often more "make your character and I'll fit you in", which kept going against this initial desire I had. So, after dabbling in DM'ing with a silly Pokemon campaign and looking into PF2e and coming to the same level 0 idea I mentioned earlier, I decided to subject my own fellow Melonmancers into taking this idea of figuring out how your character fits into the world to the extreme.
At first, I told them nothing about the game's world and story aside from just enough information about the restrictions to their character so that they would fit into the opening of the story, which amounted to a pre-teen child of noble descent, one that wasn't in line to inherit. This set them up to be in the same position as their characters as they are first introduced to each other at a party, only to afterwards be informed that their homeland was being invaded, then days later told an armistice had been brokered, and that they were being sent as hostages to the other country.
Starting with letting them roleplay out who they are in a safe environment where they can establish what they care about, I think it helped to not only let each player feel what they lost by being sent on this journey, but everyone, to some extent, knew what everyone's character had lost and understood each other's motivations in a way that a cold start in a tavern getting a job offer from a hooded figure doesn't quite succeed in presenting.
From there, the first proper arc is all about how they are shaped by this journey. Being introduced to a whole world outside of their home, Meeting potential role models, being influenced by new ideas, and finding answers to the youthful question of who you want to be when you grow up. The whole thing took character writing to a whole other realm where who the character is is informed by actual decisions made while interacting with the game's world.
That campaign ended two and a half years ago and I've turned to looking at what I'd do for my next campaign, and I wanted to take this idea in a whole other direction. Where before I had players write their character backstories through roleplay, this time I wanted to have my players write history through their roleplay. Suffice it to say this was drawn on by my interest in human history in a holistic sense and the transition from Paleolithic to Neolithic is one I don't think I've ever seen touched in roleplay or games, so I really wanted to do it and see my players found their own civilization in a world with no prior civilization. To take the idea even further, it could become a series of campaigns, with each campaign focusing on another stage of societal progress in this world the player's are building.
So I'm thinking I'll post more in here later about my ideas for this series, how I'm intending to build a pre-civilized world with opportunities and indices for players to explore, what works and doesn't work within the setting, what kinds of things done in this campaign can contribute to future campaigns, and how PF2e contributes to these.
Thanks for coming to my TedTalks. There is no TL;DR.