- “That Game Boy Horror I gave you has a secret function! I knew it'd come in handy one day, so I developed it secretly. I call it the Boo Radar!”
- —Professor E. Gadd, Luigi's Mansion
The Boo Radar is one of the various features included in the Game Boy Horror in Luigi's Mansion and its 3DS remake. After Luigi accidentally sets free all of the Boos in the mansion, Professor E. Gadd shows the Boo Radar to him. The function of it is to detect the presence of hidden Boos in the different rooms Luigi enters (though it also detects other spherical objects, such as Boo Balls and Bombs). If the light on the top of the Game Boy Horror is blue, there are no Boos in the room. If it is yellow, there is a Boo (or a Boo Ball or Bomb) in the room. If the light is red, a Boo, Boo Ball, or Bomb is very close to Luigi. When he first enters the third floor balcony, the Boo Radar goes haywire anywhere he stands in the area due to the presence of 15 Boos gathered in a single place.
- Instruction booklet description (page 22): "This will appear during the game when Boos start to appear. When Luigi approaches a Boo, the lamp will turn red to let you know."
- Instruction booklet description (page 28): "The Boo radar is a convenient function when you are wandering the mansion in search of Boos. When Luigi enters a room where there's a Boo, the lamp on the boo radar will change from blue to yellow. When Luigi approaches a Boo's hiding place in the room, the lamp will change color from yellow to red and start to blink. When this happens, examine all suspicious objects nearby. The Boo radar responds to all Boo-shaped objects of a similar size, though, so just because the lamp is flashing red does not mean you will find a Boo."
Names in other languages
|French||Radar à Boo||Boo Radar|
|Italian||Radar Scovaboo||Boo-Finding Radar|
|Spanish||Detector de Boos||Boo Detector|