It would be a world that parallels our own on quite a few aspects. There would be roughly 500 different stats for every person (standard stats like strength, intelligence, luck, and also ones like reputation, honour, and curiosity) jobs would be partially defined by classes, everyone would have a level and exp, errands become quests that give exp that would scale based on the necessity from the perspective of the giver, the difficulty of the task, and the lack of obligation.
Achievements would also grant exp, and it would be granted for accomplishments, such as being born, finishing puberty, graduating school, having a child, living 5,10,25,50,75,100+ years, getting married, ruling a village/town/city/province/nation/empire/continent/world, and also more evil ones such as publicly humiliating someone, killing your first person, etc.
There would also be two kinds of people: NPCs and PCs. NPCs have some special powers such as: vendors can go 'On Duty' which prevents them from being attacked, and can sell things to players without risk, NPCs are the only ones that can issue quests, and they can also become Tour Guides, giving tutorials to players.
PCs would be able to enter 'Rivalry' with another PC whose values are incredibly different from their own, but only if they're of a similar level, which makes their levels scale with each other, they can receive quests, probability is distorted giving them bizarre circumstances and more likely to come across people they've met before, and it's more likely to be relevant when they do. A select few 'Main Characters', have special powers that costs them something, such as being able to do things like 'Pause', 'Save', and 'Continue'.
How would this affect society dynamics?