Mass Game Retheming

Not to be confused with anomalies such as Dynamic Level Arrangement or Dynamic Level Rearrangement, which only alter level geography

Mass Game Retheming (hereon referred to as MGR) is a rare phenomena within certain copies of Super Mario 64, in which, at most, the entire game is "rethemed" by the game's Personalisation A.I. intending to create a unique experience for each player. The "rethemes" often include changes such as:


 * Changing character models in simplistic ways, such as attaching polygons
 * Changing the "temperature" of certain levels
 * Dynamic Level Rearrangement, though majorly
 * Dynamic Level Arrangement, also majorly
 * Adjusting/Removing lighting
 * Changing text boxes
 * Changing cutscenes (such as the ending)
 * Removing/Adding levels
 * Changing menus
 * Adding NPCs
 * et cetra

Rethemes
Note that these are the most common manifestations of rethemes, and may be different than what is listed

"Too Late" Retheme
Named after the (usually) changed textbox upon entering the castle for the first time, and nicknamed the "post-apocalypse"/"Bad Ending" retheme, the "Too Late" Retheme gives Super Mario 64 a more gloomy tone, implying a reality in which Bowser has triumphed against Mario (although one still usually plays as him within the retheme), or he was "Too Late" to save the Mushroom Kingdom, hence the name. Unlike most rethemes, a certain criteria often needs to be met to trigger the retheme, this differs from copy to copy, the most common being losing all lives in a Bowser level. Upon the criteria being met, several possible documented outcomes can occur, including:


 * The current file being replaced with a "Too Late" rethemed file, either with progress retained or erased, most commonly being erased
 * The current file being retained, and a separate, unused file being rethemed and the player being forced to play the file upon exiting the "game over" screen. If all files are already in use, a file that is not the current one often becomes erased in order to make space for the rethemed file.

Changes to the game often include:


 * Lighting in levels (including Peach's castle) becoming sparse or removed entirely
 * Many textures throughout the game becoming darker
 * Less NPCs
 * Existing NPCs often appear "sad"
 * More enemies
 * Instances of certain anomalous levels (such as The Bowser Room) becoming more common
 * The game becomes more difficult, difficulty and how said difficulty is achieved differs from copy to copy
 * Skyboxes changing to that of Big Boo's Haunt or Bowser in the Dark World
 * Levels such as The Princess's Secret Slide becoming inaccessible
 * Text boxes changing to account for Bowser's victory

"Metroidvania" Retheme
Named after the video game genre of the same name, the "Metroidvania" retheme locks some, if not most, of Mario's moves behind unlockables, allowing him to access new places in levels and have new ways of defeating enemies/movement. Most often, only moves that are prexisting are locked, but rarely new moves are implemented, such as reimplementing the triple jump twirl as an upgrade for the normal triple jump.

Reports
All reports are unverified, take them with a grain of salt

NOA localization employee interview
This is a snippet of a transcript of an interview with an (at the time) NOA (Nintendo of America) localization employee (who requested to stay anonymous), although most of the interview is unremarkable, the employee appears to mention an instance of MGR about halfway through the interview, when asked about challenges while localizing Super Mario 64."Interviewer: 'Did you face any challenges while localizing the game for a North American market?'""Interviewee: 'There wasn't really much text or anything, so in that regard it wasn't that tough, though there was...'""Interviewer: 'What was?'""Interviewee: 'Well, we were about 75% of the way through localization, right?'""Interviewer: 'Right'""Interviewee: 'And the game changed! I don't even know what happened, it seemed like it was overnight too, I remember coming into work the next day and the whole game was different.'""Interviewer: 'I take it the game is not supposed to do that?'""Interviewee: 'Yes, thankfully we were able to get it back to normal by deleting the file we were using, it was really strange'"

Theorizing
It has been theorized that MGR is considered rare due to the Personalisation A.I. having to either go to great lengths to "retheme" the game, or not wanting to create an experience entirely unlike that of documentation such as the boxart, though both are unconfirmed.

It has also been theorized that MGR is not actually its own anomaly, but a collection of several, already documented anomalies (such as Enemy Discoloring and Dynamic Level Arrangement); However, most categorize it as its own anomaly due to its differences from certain anomalies usually associated with being part of MGR.