The Door Master flips over the first card (Mother Load), reads out the card, and the 1-hour timer begins! (stop looking, there’s no handy timer included in the game. Just find one online, look at a clock, or find some bored kid who’s good at counting).
The Heroes work together to punch through the gauntlet 1 room at a time, clearing as many as possible before the hour is up. Once a room has been cleared, the party is automatically moved to the next and may never return.