Game pits multiple players in a closed circuit. One player controls the pump/flow where others are entities in the circuit, trying to keep the whole healthy.
Stay Inside The Box: The whole game takes place in just one screen, no scrolling or changing screens in any way is allowed.
More the Merrier: The game is a competitive or cooperative multiplayer "party game" (i.e., based on minigames, humor, 4+ players, audience engagement, etc.), meant for one screen or more.
Bigger Picture: The game touches on a political, environmental or social issue.