The player controls a stick figure who must collect all the gold in a level while avoiding guards who try to catch the player. After collecting all the gold, the player must travel to the top of the screen to reach the next level. There are 150 levels in the game which progressively challenge players' problem-solving abilities or reaction times.
Levels feature a multi-story, brick platform motif, with ladders and suspended hand-to-hand bars that offer multiple ways to travel throughout. The player can dig holes into floors to temporarily trap guards and may safely walk atop trapped guards. Should a guard be carrying a bar of gold when he falls into a hole it will be left behind, and can be retrieved by the player. Over time, floors dug into will regenerate, filling in these holes. A trapped guard who cannot escape a hole before it fills is consumed, immediately respawning in a random location at the top of the level. Unlike guards, the player's character may not climb up out of a hole, and will be killed if it fills before he can escape by other means. Floors may also contain trapdoors, through which the player and guards will fall, and bedrock, through which the player cannot dig.
Notably, the player can only dig a hole to the sides, and not directly underneath himself. This poses an important strategy: when digging through a wall X blocks high, the player must first dig a gap at least X wide to be able to dig through it, as the number of spaces will shrink with one each layer, and the player needs at least one free adjacent space to be able to dig.
The player starts with five lives; each level completion awards an extra life. Should a guard catch the player, one life is lost and the current level restarts. The player's character can fall from arbitrary heights without injury but cannot jump, and players can trap themselves in pits from which the only escape is to abort the level, costing a life, and begin again.
Source: Wikipedia, "Lode Runner," available under the CC-BY-SA License.