The corridors form an intricate maze, infested with unlikely monsters which are nonetheless unnervingly lifelike, even if they resemble nothing on earth. 
I know a ten-year-old who runs to hide when the armed skeletons appear; and a grown computer journalist once described how he spilled coffee all over his machines after being startled by a giant pink worm which was chewing on his characters. 
The plot of the games is a jumble of nonsense, apparently <tag "515647">derived</> from the sub-Tolkien world of `dungeons and dragons", which was also the source for the way in which the characters, controlled by the player, can gain in cunning and strength as well as armour and possessions as the game continues. 

