Luigi's Mansion: Biggest Threat Yet
Release date Flag of Japan October 27, 2019
Flag of USA October 31, 2019
Flag of Europe January 3, 2020
Flag of Australia February 11, 2020
Mode(s) 1-4 Players (Local)
1-8 Players (Online)
Platform(s) Nintendo Switch

Luigi's Mansion: Biggest Threat Yet (known as Luigi's Mansion 9 in PAL regions) is the ninth installment of the Luigi's Mansion series.


A long time ago, in the early ages of the Mushroom Kingdom, seven warriors donned different powers to create balance in the kingdom. However, that power could also cause chaos, and if used incorrectly, the whole world could be destroyed. An evil entity had attempted to harness this power, and was barely defeated. When the evil was destroyed, the seven warriors passed their powers down to the next generation, who passed those down to the next, then to the next. These powers would eventually be passed down to seven lucky residents of the Mushroom Kingdom.

In the present day, Luigi is going on a walk when it starts to rain. Since Peach's Castle is nearby, he attempt to find refuge there, only for the castle to suddenly shake. To his horror, the castle suddenly starts crumbling and sinking into the ground, along with the hills surrounding it. Suddenly, a green void opens from underneath him, and he falls into it.

The void leads him to E. Gadd's underground lab. There, E. Gadd tells Luigi what has been happening: King Boo had come and captured the residents now donning the special powers. To Luigi's surprise and shock, the residents are his own friends, and even his brother, Mario. E. Gadd explains that King Boo has been misusing their powers, resulting in the world as they know it slowly falling into ruin.

It is now up to Luigi, powered up with the Poltergust 400 to save his friends, and the world from the "biggest threat yet."


Luigi's Mansion: Biggest Threat Yet utilizes elements from both the first game and Dark Moon, where there are multiple locations but each one has its own set of bosses to defeat. Luigi has the feature to toggle between Standard Mode and Sidestep Mode, as well as the ability to switch his flashlight from its normal setting to the Strobulb from Dark Moon. Money in this game is similarly used to unlock ugrades and special features for the Poltergust 400. These features, once unlocked, can be disabled, but can then be reenabled for free. Some ugrades include elemental powers, which the player can toggle between. In addition, Luigi has the Game Boy Horror X, which can take images and display a map of the world or mansion.

Unlike past Luigi's Mansion games, this game takes heavy inspiration from open-world adventure games such as The Legend of Zelda: Breath of the Wild; the game heavily encourages exploration. Upon starting the game, Luigi must walk to the locations, though by finding green voids, he is then able to teleport between mansions and the lab. The game also features a built-in timer for a daylight cycle and weather. Each in-game hour is 10 seconds; during the day, the only other characters are NPCs that Luigi can encounter and play minigames with. During the night, ghosts run rampant, and Luigi has the option to defeat them.

Some NPCs have optional side quests that Luigi can do; doing these gives Luigi more rewards, such as a gem or large sum of money.

Each location has its own bosses, rooms, and gimmicks for Luigi to explore. When Luigi clears a room, it lights up permanently, and Luigi can explore the rest of the house. Eventually, Luigi finds and captures the first boss of the area, followed by the next, and then the boss donning the special powers. Once that boss is restored, the location in which is connected to the power is permanently restored.

Every room in a location has a Boo hiding. Once all of the lights are turned on within a room, the player has the option to seek out the Boo. Capturing Boos is optional, though catching more and more plays a factor in the game's ending. Each location has


  • Peach's Castle - A familiar sight, holding the power of Love
  • Haunted Jungle - An old jungle, holding the power of Strength
  • Apartment von Greed - A rundown apartment complex, holding the power of Greed
  • Nocturnal Dino Island - An abandoned island, holding the power of Kindness
  • Tower of Wah - A haunted tower, holding the power of Mischief
  • Old Sarasa - Ruins of a forgotten kingdom, holding the power of Beauty
  • Manor of Mysteries - A series of otherworldly tests, holding the power of Courage

Once Luigi defeats and rescues all of his friends, he is suddenly taken to Luigi's Old Mansion (the mansion from the first game) to have a final confrontation with King Boo.


Peach's CastleEdit

  • Yellow Toad - The Forgotten Hero
  • Toadsworth - The Wise Old Hermit
  • Princess Peach - Ruler of the Kingdom

Haunted JungleEdit

  • Diddy Kong - Partner in Crime
  • Cranky Kong - Grumpy Old Man
  • Donkey Kong - Leader of the Bunch

Apartment von GreedEdit

  • Ashley - The Demonic Child
  • Cat and Anna - The Dueling Twins
  • Wario - Richest of the Rich

Nocturnal Dino IslandEdit

  • Birdo - The Egg Spitting... Birdo
  • Kamek - The Evil Koopa Wizard
  • Yoshi - Leader of the Yoshis

Tower of WahEdit

  • Alex - The Tennis Ace
  • Emily - The Varsity Coach
  • Waluigi - Agent of Chaos

Old SarasaEdit

  • BOSS RUSH: Dragonzamasu, Biokinton, Hiyoihoi, King Totomesu, and Tamao
  • Tatanga - The Lost Enemy
  • Princess Daisy - Ruler of Sarasaland

Manor of MysteriesEdit

  • Boom Boom - The Old Rival
  • Bowser Jr. - The Youngest Son
  • Mario - The Fallen Hero

Luigi's Old MansionEdit

  • Bowser - A Possessed Koopa
  • King Boo - Master of Illusion
  • The Boodingnagian - King Boo's Strongest Form Yet!

Hidden ModeEdit

Like the first game, there is a Hard Mode, unlocked after beating the normal game. Naturally, the mode is noticably more difficult than the normal mode, with many changes:

  • The locations are mirrored, and noticably darker.
  • Ghosts, including bosses do more damage and have more HP.
  • Ghosts in general are more common.
  • The Poltergust 400 does twice as much damage to ghosts, and has a heat meter; should this meter reach 10, Luigi takes damage.
  • Time goes by faster during the day, with each in-game hour during the day is 5 seconds. After 6:00 PM, the time reverts back to 10 seconds per in-game hour until 6:00 AM, where it resets back to 5 seconds per in-game hour.


There are multiple endings to the game; a bad ending, a good ending, and the best ending.

  • In the bad ending, Luigi returns home after a long day. When he goes to sleep, however, King Boo is seen outside his window, smiling maniacally. The screen suddenly goes black, only to fade in to a shot showcasing Mario and his friends recaptured. In addition, Luigi's cap is on the ground, with Luigi nowhere to be seen. The words "THE END" is displayed on the screen, as King Boo mockingly laughs at the player.
  • In the good ending, Luigi returns home after a long day. When he goes to sleep, however, he is suddenly waken up by Professor E. Gadd. The professor informs Luigi that his work is far from over, and that he must help him with his research. With a sigh, Luigi gears up and heads out the door.
  • In the best ending, Luigi returns home after a long day, commenting on how he had not only helped E. Gadd's research, but his friends, too. When he goes to sleep, the moon is seen outside the window. The words "THE END" is displayed on the screen, and the credits play.

The bad ending is played when the player has captured 0-35 Boos. The good ending plays when the player captures 36-69 Boos. To acquire the best ending, the player must do many things:

  • Find and use every void
  • Capture at least one of every ghost.
  • Take a snapshot of every ghost using the Game Boy Horror X.
  • Complete every side quest.
  • Unlock all of the Poltergust 400's upragdes and features.
  • Clear every room within all of the mansions.
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