Core Categories
This exercise is based on the popular short-form game, "Categories."
One person will act as host; everyone else will form a horizontal line or semi-circle. The host will name a category and quickly point to one participant at a time. The participant will name a word, item, or idea from that category as quickly as they can. If they say a word not clearly within the bounds of the category, the host will declare them "out." If they repeat a word previously used in the round by someone else, they are out. If they simply pause too long, and everyone can sense more than a second of dead air, they are out. Proceed until one person is left.
That is the classic description of the game. In order to alter it to serve as a useful narrative long-form warm-up, the host simply needs to name "categories" that the improvisers will frequently need to call on while performing scenes: first names, last names, nicknames, types of rooms, types of furniture, outdoor locations, general settings, relationships, wants, high-status behaviors, low-status behaviors, analogies, similes, etc.