Game Boy Horror

The Game Boy Horror is a machine designed by Professor E. Gadd in Luigi's Mansion. It allows him to communicate with Luigi. It also has a map, Luigi's stats, the portrait ghost's descriptions, and a radar for Boos. The map and inventory are accessed by pressing and  respectively. Luigi can look in the Game Boy Horror's camera screen by pressing to allow the player to see the mansion in the first person perspective. The player can also select certain objects and have Luigi say something about it, much like the Tattle ability in the Paper Mario series. If Luigi checks a mirror with the Game Boy Horror, he will be warped back to the Foyer automatically; however, this does not work with the mirror in the Mirror Room. In the Nintendo 3DS remake, the Game Boy Horror's search function is used by pressing, while the map and inventory are shown on the touch screen.

The Game Boy Horror was designed after the Game Boy Color, specifically the Japan-exclusive clear color variant, with the "HORROR" on it even resembling the Game Boy Color's "COLOR", even though the Game Boy Advance was already released. This was because throughout the early conceptual development of Luigi's Mansion, the then-unreleased Game Boy Advance's design was wavering throughout. In Luigi's Mansion: Dark Moon, it was succeeded by the Dual Scream.

The Game Boy Horror was going to be an item in Mario & Luigi: Superstar Saga, but it was replaced with the updated Game Boy Horror SP, modeled after the Game Boy Advance SP, which can be used to get rare items in every battle and is earned after mixing every Bean Juice blend in the Starbeans Cafe. Also, E. Gadd twice contacts the cafe using a giant two-way Game Boy Horror that is capable of warping items between the two locations, demonstrating this ability during the second time. A side effect of the Game Boy Horror's arrival is that it causes a blackout in the vicinity.

Trivia

 * By pausing or using the Game Boy Horror in a dark room, one can hear that the ghosts are singing the Luigi's Mansion theme song.
 * In kiosk demos of the game, the Game Boy Horror displayed the amount of time remaining before the game would reset back to E. Gadd's lab.
 * The Game Boy Horror's more advanced features, such as cameras, backlighting, and wireless communication were not available with its real life counterpart the Game Boy Color, however each was eventually included with future Nintendo handhelds.