One of the first graphical computer role-playing games, Tunnels of Doom puts the players in control of up to four characters in a single party, to explore the dangerous Tunnels of Doom, fight monsters, and collect treasure. The four characters can be controlled by one player as a party, or by up to four players, each choosing an action during battles.

There are four different character classes available: Fighter, Rogue, Wizard, and Hero. The latter can be selected only if he is the only character in the party. Enemies appear randomly, and the battles are turn-based. Various treasure is scattered around the dungeon; the player also has the option of buying certain equipment. In some places, fountains can be found; drinking from them will affect the party in different ways, positive or negative.