Every Thursday evening, the City Council of Hound's Teeth meet to discuss the issues of the week. This is an open meeting, and anyone who wants to ask something of the council is coming. From frantic farmers complaining about the zombie they saw traversing their field, to a new religion that wants to establish a temple, to a troupe of adventurers trying to free their party member who got caught picking some Lord's pocket, everyone in the area seems to have something that they think is vitally important. Meanwhile, the council members never did finish arguing about that new irrigation system that was being discussed last week.
How many times has your party walked into a council meeting in a fantasy world with some demand? This horde LARP is what's really going on at every one of those meetings your tabletop characters have ever walked into. No knowledge of any tabletop system is required for this game.