A Dash of Boulder
From A KoL Wiki

In the Dungeon of Doom, you encounter a hallway blocked by a huge boulder. You push and push and push, but eventually reach a dead end, at which point you have to just turn around and leave.
You'll always wonder what was at the end of that corridor.
Occurs at The Dungeons of Doom.
References
- The adventure title and text refers to the video game Boulder Dash, in which your character pushed boulders around.
- This adventure also references the Sokoban levels in NetHack, which are a similar boulder-moving puzzle.
- The 'You'll always wonder what was at the end of that corridor.' refers to the fact that if you make a mistake on the Sokoban puzzle in NetHack, it becomes permanently unsolvable (without severe penalties), thus leaving you wondering what the prize was for the rest of the game.