- This game has a very different opening than the other two. Unlike them, which drops you right into the haunted locale immediately, this one has a decently lengthy prologue with all the humor, color and charm the Mario series is generally known for, with the hotel initially seeming just as inviting as advertised. Because of this, when the creepy, haunted stuff does hit, it hits that much harder, particularly as Luigi actually witnesses the glamour fade away in the hallway.
- King Boo is back and if you thought he was frightening in Dark Moon, this game takes it to a new level by giving him facial expressions other than his usual Slasher Smile. Namely, a Death Glare that suddenly appears whenever he is reminded of his previous defeats or just Luigi in general. That rage-inducing scowl with massive fangs is the face of a psychopathic ghost who wants you DEAD.
- King Boo chasing Luigi at the very beginning of the game, with the intent of trapping him in a painting like his other friends. And Luigi has no Poltergust to save himself. What's even worse is that it is possible for King Boo to catch up to Luigi during the in-game chase sequence which if he does, you'll get a special cutscene of King Boo throwing the portrait frame on top of Luigi as he screams in terror.
- The Game Over sequence is no longer a simple "Good Night" line over a defeated Luigi on the floor like in the previous games. Instead, the game happily shows you the logical aftermath: A terrified Luigi trapped as a painting surrounded by his captured friends, while King Boo admires his new collection. Then King Boo turns around and faces you with a demented Slasher Smile and Evil Laugh. Then the scene cuts to the classic "Good Night" line just to drive in the point.
- Oh and if you look closely, you can see E. Gadd there among the portraits. Just when you think E. Gadd might save Luigi and friends (assuming you rescued him from his own portrait prison), King Boo recaptures him to ensure there's no one around to save our heroes. The Bad Guy Wins indeed.
- If you explore inside the freezer room on the second floor, you'll be greeted to a giant Alluring Anglerfish waiting to chomp on you. Sure, it stops moving after it attacks note but the fact it's a realistic-looking Angler in a cartoonish game like this is unsettling to see, especially with its mouth being big enough to eat Luigi.
- The Bridge Room, a later room in the medieval-themed 6F, has its back wall dominated by a large, intimidating stone king carving whose eyes follow Luigi everywhere he walks. What really clinches this is that when you enter for the first time, the carving starts off looking straight ahead at nothing in particular (not quite even the camera), before the eyes unhurriedly slide over to Luigi. You've been noticed.
- Dr. Potter attacks Luigi with a very creepy-looking Man-Eating Plant. It looks like the venus flytraps from Dark Moon, but now with a scaly texture and Glowing Eyes of Doom. Even the ones in Dark Moon weren't so bad, but this is a far cry from the cartoony, Ugly Cute Piranha Plants of the main series.
- The first time you go down to the lobby after the resort goes evil, you see a pair of ghosts systematically sealing the front door. They've drilled planks into the doorframe and then proceeded to chain those planks up. The ghosts are making it very obvious this time that until they get their fair share of Luigi's terror, he will not be allowed to leave.
- Amadeus Wolfgeist's last-straw cutscene before he possesses his piano is pretty terrifying due to how unhinged he appears in his anger, paired with his appearance becoming disheveled and exaggerated. When he leaps into his piano, it leans forward angrily and roars with a discordant key-pound - any players who encountered the Mad Piano in Super Mario 64 as a kid probably had an unpleasant flashback, to say nothing of how Wolfgeist is also channeling his inner Ludwig van Beethoven.
- The Spirit Balls from the previous game return in this game, and they have a terrifying sibling: a magenta variant that, rather than making objects disappear, causes them to become sentient, and try to kill Luigi. The exception to their scariness is when they turn a key into a bunny that merely tries to hop away from Luigi.
- In the Unnatural History Museum floor, as soon as Luigi opens the curtain in the back of the elevator room, a dimly-lit exhibition room can be seen at the end of a long hallway with a T-rex skeleton illuminated by frequent lightning strikes outside the windows. When Luigi begins walking down the hallway, occasional lightning flashes will illuminate the whole room ahead for just a second, after which the T-rex's head has turned to gaze in the direction Luigi is standing in at the time. This is the only clue given that the T-rex will be a boss fight before it is already looming over Luigi as he tries to free Yellow Toad from his portrait.
- The Master Suite. Before now, Hellen Gravely's idolization of King Boo was obvious, but it seemed pretty tame as far as fangirling goes, right? And then you reach the top floor of the hotel, and find the entire place is basically her giant Stalker Shrine to King Boo: Paintings of her and the King together, shelves upon shelves of trophies in the King's likeness... even the gems for the floor are all shaped like him. If realizing just how far Hellen's obsession goes doesn't make your spine tingle, a lot of the memorabilia should damn well do the trick; some of the King Boo trophies have horrifying grimaces plastered onto them, and one of the illustrations of the good king is recessed, so it "watches you" and follows your movements. Considering this is King Boo we're talking about, you'd expect something out of all the statues and paintings to go the extra mile and attack you, but aside from one statue hiding a bomb if you vacuum on it too long, none of them ever do...
- The stalker nature of Hellen goes even further once you take a look at her outfit. She's wearing a white dress with a cutout in the shape of a diamond that shows her purple skin. It's like she's trying to wear King Boo on her body.
- Poor Luigi is frequently caught in harrowing situations that either require Gooigi or quick thinking or both for him to escape and survive. He's grabbed by a plant in the Garden Suites, can be entangled by Trapper ghosts, and gets stuck in a prison cell while spiked walls push in on him. Then there's the puzzles on floor 10, featuring death traps that seem like something right out of Resident Evil. First, there's a puzzle where three laser turrets come out of the floor and begin beaming the chains holding up the ceiling. Fail to disable the lasers in time and Luigi is flattened into a Luigi Sandwich. Then there's another puzzle where you need to place weights and sand on a scale and flash a switch to make the needle land on the animal shown above the switch. The problem? The spikey ceiling is slowly coming down on you (sound familiar?). Finally, you're trapped in a room that is filling up with poison gas that slowly chips away at your health and the only way to stop it is to launch the matching gems into the holes to block them. Easily the most terrifying traps in the Luigi's Mansion series, maybe even the Mario series overall.
- Hellen's pet, the Polterkitty, seems like a wimp at first... until she reveals she can turn into a larger form that looks very realistic. Worst still, to catch her, you have to bait her into attacking you, and her window of vulnerability is literally the last second prior to striking. Imagine having a beast stalking behind you preparing to hurt you badly... though the nightmare aspect is hampered slightly in that you can have Gooigi on standby to stop her in her tracks.
- After spending the entire game as Luigi catching ghosts and rescuing his friends, King Boo confronts him on the hotel's roof, and proceeds to re-capture everyone in a painting like it's nothing. And he had every intention of adding Luigi to his "ensemble painting." If Polterpup hadn't unintentionally knocked Luigi out of the way, King Boo would have won right then and there.
- The final boss against King Boo. You and Gooigi beat the crap out of him, and after all he's put you through, it must be a great feeling. You got this in the bag right? Wrong. Just as you think you got him cornered, he enlarges the painting that Mario and co. are trapped in and begins to bring it down on the entire hotel in a desperate last-ditch effort to capture Luigi once and for all, and he's in the painting's collision course, too. You then have four minutes to defeat him or everyone will be sealed away in a portrait, and King Boo will happily join Luigi and friends inside if it means getting rid of him forever. That's how far King Boo is willing to go just to get revenge on Luigi.
- Of course King Boo is fine with being caught in the painting with Luigi... He's already escaped from paintings by himself in the past!
- In general, the Last Resort is never safe. Unlike the previous mansions, the ghosts never fully go away. Go back to an old floor that you cleared, and you can occasionally encounter more ghosts to face. Even the safest floor, the basement, isn't that safe. While escorting Toad in the late-game, you'll be ambushed in the basement by some Slinkers (tougher than the average mooks). At another point, some mooks do take the initiative ambush Luigi in the elevator. It only happens once, but if it could happen one time... Not to mention the fact that King Boo does go out of his way to ambush E. Gadd's laboratory while Luigi faces off with Hellen, implying he knew they were there the whole time. In no uncertain terms, you are behind enemy lines, and there is no safe haven.
- Johnny Deepend starts off as a pretty obnoxious ghost, but once you drain the pool, he begins to scream in a startlingly realistic fashion. It's not as extreme as other examples, but since most of the boss ghost dialogue is gibberish, Johnny's screaming can be really unsettling.
- For arachnophobes, this game doesn't mess around:
- Looking through the peephole in the hotel lobby for a few seconds will present you with a screen full of a spider walking over the hole. It then exits through the hole when you exit.
- On Floor 5, exiting the eastern window and following round the corner leads you into an crawl space. At first nothing seems wrong until you notice the creepy music start up shortly followed by the space being filled to the brim with spiders.
- On one set in Paranormal Productions, you'll find Morty's megaphone caught in a giant web. Opening the cardboard box in movie mode will cause a Jump Scare in which a giant spider lunges out at Gooigi. Luckily you'll quickly see it's fake but still.
- For a sense of catharsis, you can set it on fire too.
Nightmare Fuel / Luigi's Mansion 3
All Spoilers Are Unmarked!