An Advanced Dungeons & Dragons RPG module (Dungeon Module S3). Written by Gary Gygax, the creator of AD&D, this was an incredibly frustrating module in that it consisted of an AD&D party that went out to investigate some strange occurrences (like, say, tentacles) and found what is clearly (to the players) a crashed spaceship. However, since AD&D is fantasy-based, your characters were unable to grok this, and spent their time wandering around this strange metal dungeon wondering why it wasn't made of stone. The near-schizophrenic level of detachment required to play well while holding this maintenance of willful ignorance drove many AD&D players to flatly refuse to have anything to do with it.