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 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 slwoly falling into ruin.

It is now up to Luigi 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. Many elements from the early developments are also used, including Luigi's controls and a heat meter for the Poltergust.

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 restored.


  • 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

Once the main mode is complete, the player will be able to replay the entire game on "Hidden Mode". This is the hard mode of the game. Luigi now has less HP, attacks to double the amount of damage, and the Poltergust overheats quicker. Beating this mode unlocks two unlockable costumes for the game, as well as the ability to play as Mario.


If two or more Switches are present, up to four people can explore and beat the game locally. However, because of the added players, the game will make things mire diffuclt, such as increasing damage done by ghosts, which doesn't normally happen until the Hidden Mode. While the main mode is unavailable online with more than four people, up to eight players can participate in different minigames, which are unlocked after completing Peach's Castle.


There are two endings to the game; a bad ending and a good ending. To achieve the good ending, the player must do the following:

  • Clear all of the rooms, including boss rooms
  • Locate a Boo hidden in random rooms in each location
  • Acquire 10 or more ghost gems in each area

If one or more of the objectives are not accomplished, the bad ending plays. The ending will show ghosts returning to the mansions, and reviving a fallen King Boo. However, the good ending will showcase the game's credits, and unlock upgrades for the Poltergust.