In BLACK MOLD you are an escaped prisoner trying to find your way out of an abandoned subterranean prison compound. Black undulating fungal growths coat every surface of these corridors, emitting ghostly clouds that poison the air. To avoid breathing the harmful, hallucinogenic mist, you must limit your exposure and make your escape.

This is simulated in the game by limiting the length of your turn to how long you're able to physically hold your breath.