Ultra Mode

Hard Mode is a seemingly scrapped alternative gamemode found rarely through Personalization. It generally aims to make the game harder by increasing course difficulty, reducing player health, making the player take more damage, and/or introducing entirely new mechanics and locations. There is usually a "special reward" hinted at for completing this mode which is so far undetermined.

Unlocking Hard Mode
Hard Mode usually appears in the form of a "New Game Plus" after the player has achieved any ending. It is always showcased to the player as an optional extra challenge, usually revealed in the form of a dialogue box that tells the player that Hard Mode has been unlocked, and offering it to be enabled. Following this, any save files made in the future will be given the option to enable Hard Mode. Some reports have also claimed that Hard Mode is unlocked via the Big Bully Key.

Notable Differences
The most often difference in Hard Mode is enemy A.I. Enemies will usually move faster and be able to predict where the player is moving. In most cases, they will also have increased damage and may even take multiple hits to defeat. Rarely, enemies may be given new attack patterns as well. The player can sometimes encounter Red Stars that, when collected, make these enemies and the game in general even more difficult.

Mario's appearance in Hard Mode is also updated, usually by replacing the M symbol on his cap with a "H", presumably "Hard". In some reports, the player may even control another character altogether, most commonly Luigi. The player's health is also reduced, almost always being cut in half. The player's moveset is also sometimes altered to remove mechanics such as punching or even helpful glitches to make the game even more difficult.

Bowser in every reported appearance of Hard Mode has had increased HP, with more bombs being in the arena as well. Bowser usually has differing dialogue aswell, although sometimes simply uses the standard dialogue.

Stages sometimes use different skyboxes; Daytime based stages will change to have night time skyboxes, Bowser levels will have darker ones, and night-time stages may have entirely black skyboxes. Items such as coins, 1-Ups and power-ups in general are often much less common. This can notably make some Power Stars impossible to collect, by removing necessary Caps and making many 100 coin stars impossible to obtain.

Anomalous Phenomena
Many personalisation-related phenomena appear to be removed entirely while in Hard Mode. This usually removes anomalous courses, locations, and mechanics. Some particularly major phenonema like the 2nd Basement may still be present, however. This results in almost all Hard Mode versions of the game having a decreased maximum Power Star count than the regular game, as courses are removed.

This notably makes the game, to date, entirely impossible to clear in Hard Mode, as Star doors require more stars than it is possible for the player to obtain. There may be undiscovered locations or mechanics that allow the player to progress, but no reports have found these to date.

Friendly Toads have also always been reported to have unique dialogue when playing in Hard Mode, a transcript is below. In this report, Hard Mode changed the player character to Luigi.

"Boy, Luigi, you sure have your work cut out for you, huh?

With Mario gone, everyone is beginning to lose hope...

''But I think you can pull it off! Here, take this Power Star, you'll need it!"''

Impossibility Phenomenon
As stated above, every currently reported version of Hard Mode makes the game impossible to complete. This appears to be an unintentional side effect of Hard Mode's affect on other anomalous phenomena, however some have theorized that this is an intentional mechanic that requires the player to use glitches or other as of yet unknown mechanisms to progress. The "special reward" often mentioned in copies that contain Hard Mode is, as a result, currently entirely unknown. Common theories state that this reward is a special Power Star, a new Cap, a new Playable Character, or perhaps something more.

To date, every form of Hard Mode has had the Castle Courtyard entirely unaccessible, due to a Star Door that the player cannot open. This is almost always what prevents the game from being completable, as Big Boo's Haunt becomes locked. It is commonly believed that the Courtyard may be altered or entirely different, however due to it's nature as inaccessible no conclusions can be drawn.

Players have reported extreme frustration with the game being impossible to complete, and have reported spending hours or even days playing the game. These may be hyperbolic, however due to their number it is believed that Hard Mode may have some psychological effect on it's players, causing some form of determination or drive to complete the game. Work into studying Hard Mode is underway, with attempts to clear the mode in progress.