(for building out something that is already in progress)
Draw a compressed geographic map of the region of something you’ve already started writing or imagining. Even if it isn’t located in a coherent place, treat all the locations as neighboring. Even if your writing is abstract or unlocated, treat it as located in abstract, symbolic places. Your map can be out of scale and selective, like an advertising place-mat or the frontispiece of an old children’s book. After you’ve sketched the map, populate it with newcomers, visitors, ghosts, and legends. Who comes into this space, who lingers, who reacts? How do they pass through, where have they come from, where will they go next, in what kind of vehicle do they travel? You can include other things than people: is there a flow of goods? A migration of animals? Then write the story of one of those incursions in exactly 100 words.