Dungeons and Dragons emphasizes the Dungeon Master’s role as the creator and impresario of the game. The DM creates the world, creates the NPCs, creates the story. The players, for the most part, are only really responsible for their own characters, and maybe a few related sub-NPCs like familiars, cohorts, or animal companions.
I like to introduce a small element of collaborative storytelling into the game by giving my players a resource they can expend to influence story points or newly introduced NPCs.
The rules below are draped in language that integrates them closely into my campaign setting, but really, it’s a completely system agnostic house rule. You could easily call these Plot Points, Fate Chips, Destiny Tokens, anything you like. I call them Warp Chips, because the Warp is a thing.
This house rule only affects the development of the story and the world. It doesn’t have any direct impact on game mechanics, so you can easily make use of it in any game system.