Heroscape Underworld is a solitaire or cooperative game for 1-4 players in the mold of Warhammer Quest or Advanced Heroquest. Players choose a figure (or make their own using Kaiyu's Heroes of Scape), choose a Quest and, while they play, generate an "Underworld", or series of tunnels, to explore. Random adversaries try to ambush the player figures, emerging from shadows, hidden doors, and even dropping from the ceiling in an attempt to prevent the player figures from achieving their goals. If the player figures make it to one of three fabled treasure chambers, they must face a final conflict before emerging, victorious, from the Underworld.