Legend of Grimrock invites the main character to explore the ancient underground world. The user finds himself in a fantasy universe. The protagonists are a squad of 4 prisoners. They were sentenced to exile on Mount Grimrock. To be released, the prisoners must go on a dangerous journey. It consists in the fact that it is necessary to go from the top of the mountain to the foot. This route runs underground.

In Legend of the Gloomy Mountain, a variety of explorations and quests await the user. After the prisoners found themselves in the underground world, they began to solve puzzles. They are mysterious tombs and labyrinths that need to be explored. All the time, the prisoners follow a mysterious voice that appears in their dreams. In addition, it turns out that there are notes in the dungeon. They were left by Toorum, who was also a prisoner. The notes are clues to puzzles and riddles. They are also the key to hiding places, of which there are many in this underground world.

To survive in Mount Grimrok, prisoners will have to engage in battles with different monsters and learn magic spells. This will reveal the secrets that the dark mountain has. Not only monsters pose a danger to the main characters. Very dangerous traps await them. And solving puzzles also allows you to get new equipment, which will be useful for fighting enemies.