Agreed. It also introduces an element of surprise. And also gives you a source of narra "constrains" while you are playing. This tends to help everyone come up

Agreed. It also introduces an element of surprise. And also gives you a source of narra "constrains" while you are playing. This tends to help everyone come up with interesting ideas. I lean toward games like dungeon world (http://dungeon-world.com/downloads/Dungeon_World_Play_Sheets.pdf http://dungeon-world.com/downloads/Dungeon_World_Play_Sheets...) that provide a set of lightweight rules and teach how to keep the flow of the adventure so that everyone has fun.