Make a few mini game versions, eg rooms of 20, everyone has 10 seconds to write something, 5 seconds to vote in which goes in, person with most voted-in things wins the round and/or gets to set the base pic for the new room. Rotating or random themes for the sorts of things you can suggest, edit wars where teams have to get something edited towards their end-state goal, while the other team is promoted edits for something else.

A bunch of game modes like this, freemium ad supported where paid versions or in game currency lets you setup custom games, private rooms, “super prompt” power where your prompt gets 2x the weigh.