List of Luigi's Mansion pre-release and unused content

Early Ideas
Concepts for Luigi's Mansion were in planning during the Nintendo 64's lifetime.

Luigi's Mansion was originally built with the intention of being in 3D. The GameCube was built with 3D components which could be activated by an unreleased add-on (that would have cost more than the console to buy). Another unreleased add-on would have allowed the Game Boy Advance to be used as an external Game Boy Horror in conjunction with the game, however the Game Boy Advance wasn't concrete enough that the developers could utilize these ideas. Concepts from this second add-on were reworked into the Nintendo GameCube-Game Boy Advance link cable, which allowed the GameCube and the Game Boy Advance to establish connection and play games. It is not compatible with Luigi's Mansion, as the cable was developed after the game was released.

Different kinds of houses were proposed for the game, including an apartment complex, a dollhouse, a 'ninja mansion' and a Japanese-style house. The game was originally conceptualized to resemble the Mario series more closely, but strayed when the haunted western mansion concept took priority.

It is speculated that the original plot of Luigi's Mansion involved Luigi having to save Mario within 24 hours or else be possessed by ghosts and/or watch the mansion disappear with Mario still trapped inside.

Early Iterations
The game was first revealed at Nintendo Space World 2000 as a Tech Demo designed to show off the graphical capabilities of the Nintendo GameCube.

Luigi's Mansion was later showcased at E3 in 2001, with notable changes to the design of the disc. A newer version of the game, more closely related to the final version, was later revealed at Nintendo Space World 2001.

Early Builds
Old issues of Nintendo Power (pictured below) contain details of early elements in screenshots and descriptions. The issue makes note of an unused Hunter Portrait Ghost who would have wanted to add Luigi's head to his collection of other heads. This Portrait Ghost would have appeared in the Safari Room and may have been removed due to the fact that his dialogue would have frightened younger children.

In earlier builds, the Poltergust 3000 was originally named the Poltergust 400. The Poltergust 400 featured a pressure meter ranging from one to ten, was slightly bigger and supposedly heavier. If the pressure meter reached ten, the vacuum would burst into flames, causing Luigi to fall over and lose health. Luigi did not stun ghosts to expose their heart, merely shining the flashlight on them for an extended time was enough. Earlier versions of the game allowed Luigi to spray water infinitely. In a boss battle, It was shown that Luigi could ride the on back of the vacuum and maneuver himself to capture the ghost.
 * Poltergust

Almost all of the meters in the game have gone through slight changes. The ghost meter was originally much more similar in design to the elemental meter, showing how many ghosts the player has captured instead. The Boo meter was shown as a whole number, and the amount of health remaining was shown as a fraction and written inside of the heart. In later revisions, the heart is shown as a whole number positioned outside of the heart, and the Boo meter is shown as a fraction. Interestingly, Coins had their own meter that was removed in later stages of the game's development.
 * HUD Changes

The Game Boy Horror also had features that aren't present in the final game. Originally, the Game Boy Horror had an LCD border which would function as a radar to show Luigi the locations of both Ghosts and Boos within a room, and had a clock function. It is speculated that this clock function was related to the original plot of the game. Minor changes include the design of the menu icons (earlier designs depicted icons that were cartoon-like) and that the Boo Radar's signal emitted a different sound. Early game play images reveal that instead of showing Luigi his current gold total, the Game Boy Horror would always display the first-person view, giving the player two perspectives in a room at once. This is not possible during normal game play. It was also stated that to summon Madame Clairvoya, Luigi had to check the crystal ball with the Game Boy Horror. In the final build, Luigi uses his flashlight instead.

A playable demo revealed many room layouts that differed from the final version. The Mansion had 3 top windows, no visible chimneys and no grave stones. A broken horse-drawn carriage resided outside the gates of the Mansion. E. Gadd's Lab was notably missing, and the front yard was bare.
 * Room Changes
 * When a room is completed, spinning circles of coins would appear. In the final game the coins are stationary.
 * The Foyer was originally called the Entrance, and the door to Area Two was not locked and featured a different texture. The mirror in the Foyer had no cloth covering it, and Toad was missing.
 * The Parlor was called the "Living Room" and it's furniture was arranged differently. The room had an extra side-chair pulled out in front of the china table (which had cloth on it), the paintings on the wall were ghosts (in the final game they are humans), and the door to Anteroom was boarded up. The table to the right had no tablecloth. One sofa was positioned at the left of the room and two other sofas were seen to the far right. Blue ghosts were seen playing cards, and could be battled. An image of blue ghosts playing cards appears near the Ghost Portrificationizer in the final game, whereas the ghosts themselves are missing.
 * The early Wardrobe Room had a green treasure chest.
 * In the Study, the chair next to where Neville sat, had a table.
 * The Master Bedroom was originally called "Bedroom 1". It had two beds instead of one, with a shared drawer between them. A wardrobe was positioned at the far left of the room that is not there in the final game.
 * The Nursery was originally called the "Child's Room" and Chauncey was missing, as well as any pictures of him. Instead, the room was filled with ghosts. A stuffed rabbit and two teddy bears were to the far right on a shelf, and the crib was further from the wall. There was no treasure chest containing the key to Area Two, as the door was accessible from the start.
 * Many doors were originally boarded up. Doors leading to the basement, Ball Room, Laundry Room, Sealed Room, and Fortune-Teller's Room were boarded up.
 * The Dining Room was accessed by another door beyond the Area Two door, in it's own hallway. The Dining Room had many beta ghosts residing in it, and did not include Mr. Luggs. The doors to the Billiards Room and the Projection Room were boarded up, and a china cabinet was positioned between the two.
 * The Kitchen had many ghosts, including two unseen chef-like ghosts.
 * Skeleton Ghosts did not appear in the Boneyard. Orange Punchers and Flying Fish were originally present. The area where Bogmire resides was missing.
 * The Bathroom was called the "Lavatory" and had only Boos residing in it.
 * The second floor was blocked by stacked boxes.
 * The Conservatory had a saxophone and a french horn hanging on the wall, a staircase that Luigi could climb and a blocked door.
 * The hallway after the Area Three door lacked Flying Fish.
 * The Telephone Room had gold mice.
 * The Breaker Room featured a different layout, and Flying Fish. The switch was absent.
 * The table in the Sitting Room had no cloth on it.
 * The Safari Room didn't have tiger mats on the floor, but on the tables.
 * Ceiling Surprises, Purple Bombers, and Bowling Ghosts did not appear in most hallways.
 * The Gallery had to go through many changes
 * First Gallery: The first gallery had no angel statues, was shorter, had a wall texture similar to that of the training room, and had an underground look to it.
 * Second Gallery: It had unicorn statues instead of angels and was a bit longer than the first one.
 * Thrd Gallery: It was the same as the second one, but was a lot shorter and was linked to the final gallery room.

The playable demo also revealed early ghost behavior and locations, as well as beta ghosts.
 * Early Ghosts
 * The demo and versions of Nintendo Power featured a ghost species that is unseen in final versions. These ghosts were similar in appearance to Gold Ghosts and were named 'Purple Bashers'. Purple Bashers would attack Luigi by scaring him from behind, causing a cut-scene to play that showed Luigi screaming and losing 50 HP. It is unknown why they were removed in the final version.
 * In earlier versions of the Kitchen, ghosts which resembled chefs would attack Luigi by throwing food at him. This method of attacking may have been recycled into the Hiders from Luigi's Mansion: Dark Moon.
 * Orange ghosts were white/light pink (similar to the Grabber Ghost's color) and had smaller eyes, fangs, a row of teeth, and different shaped heads.
 * Blue Twirlers had a purple color, fangs, teeth, small eyes and a big nose.
 * Boos had a basic design, lacking tongues and having more teeth, were more common, and easier to capture.
 * Gold Mice and Bats were colored white to resemble ghosts.
 * All Portrait Ghosts had 50 HP and gave coins instead of HP orbs. Upon defeat the player was rewarded a green treasure chest filled with coins.
 * Neville was significantly easier to capture.
 * Lydia did not use a mirror, and looked at the player directly. Other ghosts had to be captured before Lydia.
 * Spooky's personality was different.
 * Nana did not cry while being vacuumed.
 * Flashes were silvery ice in color, and behaved like Purple Puncher ghosts.
 * Chauncey and Bogmire were missing, as the Area system was not present.
 * Mr. Luggs was missing, as were numerous other Portrait Ghosts.
 * The demo ended with the player fighting Boolossus, thus all Area 4 Ghosts were unseen. Boolossus was smaller and had no tounge.
 * King Boo's design changed drastically. His original design resembled a Big Boo, and did not wear a crown.
 * At the end of Space World 2000,A two second cutscene was aw showing three ghosts playing cards on a table, the ghosts did appear in the full game, but only as a picture that was seen when Mario went in the Ghost Portaficizer.
 * Other
 * Decorative vases and candles were coloured red, instead of blue.
 * The cut-scene showing Luigi opening the door to the mansion was slightly different. The door was also designed differently.
 * There were four unused dialouge icons.
 * Bowser
 * Green Toad (which is present with Action Replay)
 * Gold Ghost
 * Mario

Nintendo 64 Belief
There has been evidence that Luigi's Mansion was going to be a N64 game.
 * 1. When Luigi picks up one of Mario's item, the sound would be the same as when you enter a painting in Super Mario 64
 * 2.There was a poster showing Daisy entitled "Test.bti" in the demo and the image was Daisy from Mario Tennis 64.

Trivia

 * The Japanese version of the game kept Luigi's BETA hurt sound while US and Europe versions didn't.
 * The GBH's timer and first person view is still in the games code and has been found and made into AR codes.