Another game that handles flags really well is Legends of Wu-Lin. It’s very much a game about living in a world of mystical martial arts and power warriors, but you only gain XP, called cultivation in the game, by investing in the story, by telling the GM and the other players what things you are interested in exploring. You are even given points to specifically invest and engage with other peoples “flags’ (i forget exactly what they are called in the game) which encourages the group to take some of the heavy lifting off of the GM when it comes to tieing everyone together.

Sadly its almost impossible to find in hard copy, and I’m not sure its still available legally in PDF which is a shame, its a great game and deserved more attention than it received.