Full Context
When the Nintendo GameCube released in the year 2000, there was no Mario game to accompany it. Luigi instead featured in what would become the first installment of the Luigi’s Mansion sub-franchise; a comedy-horror series in which Mario’s cowardly brother explores spooky locales and captures ghosts using a vacuum the Poltergust.
Though a commercial success at the time, the game received a mixed reception by critics and audiences alike. The release of Super Mario Sunshine the following year helped overshadow Luigi’s adventure, and it would remain a one-time spin-off until over a decade later. Nintendo handed Luigi’s ghostbustin’ side-gig over to Next Level Games, who were previously responsible for the Mario Strikers games. Luigi’s Mansion: Dark Moon released as a 3DS exclusive in 2013, and Luigi’s Mansion 3 became a Switch exclusive follow-up that released in 2019.
Story
The story takes the familiar Mushroom Kingdom crew to a luxury hotel, which quickly turns out to be a ghastly trap. The beauty-obsessed hotel owner and all of her staff are actually ghosts, who are working under the banner of King Boo; Luigi’s nemesis throughout the series.

King Boo initially attempts to capture Luigi at the start of the game, but then vanishes from the plot as the level-by-level structure of the gameplay sets in. We know he’s there, but the spooky royal is afforded little presence throughout the game, and even the various Boo henchmen are merely treated as an obnoxious side-objective if you choose to revisit previous levels.
His inclusion makes it feel like the developers felt obligated to have him as the final boss, simply because the prior games did so too. Luigi’s Mansion 3 has a much stronger villain in the hotel owner, Hellen Gravely, who frequently stars in cutscenes, has more dialogue with Luigi, sends her cat familiar to harass you on some floors, and has a fantastic boss-fight just before the confrontation with King Boo. He is overshadowed.
The build-up to the actual battle is strong, however. After defeating Hellen, Luigi saves Mario from King Boo’s painting and the two head up to the hotel’s rooftop. Nintendo and fans have long played around with the idea of Luigi being envious of his heroic brother, and this section plays with that to great effect. Mario ignores the eerie atmosphere of the final corridors and frequently jumpscares his brother by accident. He also effortlessly jumps and cheers his way past perilous obstacles, while Luigi and his heavy backpack have to inch their way past them.
We eventually catch up with Mario on the rooftop and free Peach, only for King Boo to make his appearance and promptly imprison the cast in a painting all over again. Luigi just barely escapes, sending King Boo into a menacing tirade.
King Boo is still a good character and a beloved mainstay villain of the Mario universe, even if his inclusion in Luigi’s Mansion 3 could have been better. Since he is still a convincingly-fearsome foe, I give this category an average…
Presentation
Following the great build-up towards the battle proper, the actual arena is a tad disappointing. It’s a flat, square box with no decoration save for a few dimmed lights on the edges. The actual decor of the hotel exterior is kept just out-of-sight. It makes the battlefield sterile, which does admittedly help you focus.

King Boo himself has come a long way since his OG appearance in the mainline Mario games. He used to just be a Big Boo with a simple crown, but Luigi’s Mansion 3 turns him into a frightening bad guy. The heavy shading on his… body(?) negates the lovable glow of typical of Boo-type enemies in these games, which goes paired with his enormous fangs and glowing eyes. He looms over the field and constantly leans in to intimidate Luigi to great effect.
The music is… unimpressive however. It’s a generic battle theme that could have fit in almost any other game and doesn’t properly convey the excitement of a final boss. The King himself has some spooky sound-effects, but the battle as a whole is low on atmosphere.
Battle Mechanics
Though earlier boss fights were designed to feel dynamic and involved, King Boo uses a basic setup where you dodge a sequence of attacks and then counter-attack. His moves are diverse enough to require different strategies to dodge, but it gets boring waiting for your turn to actually do something while King Boo spends literal minutes chaining together attacks you can only react to.

Your opportunity to counter-attack is a bomb you have to fire back, but dodgy targeting mechanics combined with the far-away, isometric camera angle make hitting King Boo more annoying than it has a right to be. And if you can’t capitalize on this one chance to do damage, you are put right back on the defensive for however long it takes for the bombs to come back up.
This is especially egregious in the final stage of the battle, which adds a 3-minute timer. Why time the player on something they can’t influence much? You either hit Boo on the one or two opportunities you get, or the timer runs out while you wait.
Adding ways to hurt the boss during the other attack patterns could alleviate this problem, without sacrificing the intended difficulty if the required amount of hits is upped as well. This would (ideally) also provide opportunities to use all your tools, since the fight normally only requires the basic features of the Poltergust. As it stands, the fight is not engaging enough for what ought to be an exciting finale. Especially the targeting problems are painful, because this exact problem plagued the King Boo battle in the original Luigi’s Mansion.
Challenge
Luigi has 99 health throughout the entire game and, like all other bosses, King Boo deals 20 damage per hit. Instead of increasing the damage output, the fight is made more challenging by reducing the amount of hearts that can be dropped. Prior bosses would often drop health pickups faster than they could deal damage, whereas the king rarely slips up.

The attack patterns are manageable to dodge, so being hit always felt like it was my own mistake, and not being able to easily refill lost health added to the intensity of the battle. The patterns also become more elaborate as King Boo creates an extra clone of himself in each phase of the battle that acts semi-independently. It’s a simple but effective way to up the challenge between each phase, though these clones also add to the frustration of dealing damage yourself. There are ways to discern which targets are fake, but spotty aim assist and the high pressure you’re working under make this unfairly challenging when held against the punishment for messing up.
King Boo is a boss you’ll want to bring a few extra golden bones to. While I could reliably defeat prior bosses with just one bone in case of bad luck, I had to retry King Boo several times using this same setup. All in all, the fight has a nice level of challenge, which is only frustrated by the lackluster mechanics.
Overall verdict
I found King Boo to be a lackluster battle to end an otherwise strong game on. It builds a lot of excitement for an encounter that ends up being obnoxiously by-the-numbers, on top of already being a tacked-on inclusion after a much better boss battle. Not bad enough to ruin the game at the last moment, but a major disappointment when compared to other final battles in major Nintendo games.