Game Boy Horror

The Game Boy Horror is a machine designed by Professor E. Gadd in Luigi's Mansion. It allows Professor E. Gadd to communicate with Luigi. It also has a map, Luigi's stats, the Painting Ghost's descriptions, and a radar for Boos. Luigi can look in the Game Boy Horror's camera screen 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. It can also be used on mirrors to teleport back to the Foyer. (excluding the mirror in the Mirror Room)

The Game Boy Horror was designed after the old Game Boy Color even though the Game Boy Advance was already released. This was because throughout the the early conceptual development of Luigi's Mansion, the then-unreleased Game Boy Advance's design was wavering throughout.

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, which can be used to get rare items in every battle and is earned after fixing every blend. Also, Prof. E. Gadd occasionally contacts the Starbeans Café using a giant two-way Game Boy Horror that is capable of warping items between the two locations.

Trivia

 * Pausing or using the Game Boy Horror in a dark room, one can hear that the monsters are singing the Luigi's Mansion theme song.
 * If Luigi targets a mirror with the Game Boy Horror by pressing the button instead of pressing the  button when he aims at it, he will be warped back to the Foyer of the first floor automatically, however, this does not work with the mirror in the Mirror Room.
 * Interestingly, if the player uses the Game Boy Horror's map function in the Training Room or the Gallery, they can see that there are four rooms connected to each other: the latter two, the lab, and the Ghost Portrificationizer room. There are also several doors visible in some of these rooms, but they are inaccessible; if the player tries to go through the one in the Training Room, it will not be possible. E. Gadd stands in front of the one in the Gallery. Also, on the map, there is a ladder visible in the lab; this possibly means E. Gadd's headquarters are underground.
 * The Game Boy Horror may be a parody of the Ghostbusters' P.K.E. Meter, just like how the Poltergust 3000 is a parody of the proton pack and ghost trap.
 * The HORROR letters on the Game Boy Horror appear to be the letters modeled after the letters of the Game Boy Color's words, COLOR.