An arcade puzzle game where you must tunnel your way through a number of underground caves, collecting the many gems spread throughout the levels. Each cave is litterered with rocks which, should they fall onto you, will result in a loss of life. Carefully planned tunnels can be dug to manipulate the direction in which the rocks fall, however, which makes them an effective weapon against the many enemies that populate the levels. A number of red explosives can be found which can also be used to kill enemies and also to destroy any walls blocking the your path. Again, like the rocks, these must be used carefully to prevent the explosion from killing the player.

In order to complete a level, a specified number of gems must be collected. Once a sufficient amount of gems have been collected, an exit will open which the player must enter to proceed to the next cave.

Diamond Run is heavily based on First Star's Commodore C64 classic, 'Boulder Dash'.