I just wanted to tell you, I've just returned to this game after a while, and I had an idea for jokers that make them more than just prompts to stop playing! My idea is that jokers serve as freeform prompts of an exceptional nature! Since they are so rare, especially if you reshuffle the deck after each game day like I do, they represent an interruption to the usual day to day in the library where something out of the ordinary, even by the library's standards happens! Also the intention is to keep it vague so this could cover a whole range of scenarios, but the one thing joker events must have in common is being suitably epic, while staying within a slice of life tone of course! Finally, of course, like many of your game's rules, this way of playing is to be completely optional.