Rhem is an adventure game in which the player explores a barren, maze-like landscape of water ponds, walkways, and brick buildings with the aid of a partial map. The game has several puzzles involving machines and symbols.

The player enters the city of RHEM on a railway car. The car goes into a dead-end station with a rotatable track. The player is unable to leave because the track is not yet rotated. While the player is on his way to the switch to rotate the station track, a previous prisoner of RHEM beats the player to the switch he was after and leaves in the player's railway car. The player must then wander the city of Rhem in search of a second railway station.

Each of the quarters of the letter is located in a different area not shown on the map provided in the game's package.