B3313 is an ambitious hack of Super Mario 64 Christopher Rios Lillo (aka ChrisRLillo) and his dev team based on the internal plexus theory. It was originally developed from 2021 to 2023, but was abandoned due to health issues. It is currently unknown whether the project will be complete.

Update Feb 2024: There’s now an even newer version which fixes some bugs and adds a new area making a total of 471 stars in the game. You can find it at the very bottom of the downloads page.

You can download the ROM patch on the downloads page using the password internal3313plexus, or from archive.org. Then apply the patch using BPS/FLIPS to a SM64 ROM called Super Mario 64 (U) [!].z64. This hack won’t work on a real Nintendo 64, so instead use an emulator.

Internal plexus & personalisation AI theory

B3313 is based on what is called the Internal Plexus theory and the Personalised AI theory.

The personalised AI is a conspiracy theory behind the mandela effect that a lot of people have while remembering Super Mario 64. The idea is that everyone who played Super Mario 64 back in the day remembers things to be slightly different – a missing goomba, a differently-shaped cliff, a texture that seems off… Everyone has a slightly different way of recalling the game.

Some people online came up with a theory that every cartridge of Super Mario 64 had within it an artificial intelligence that adapted the game to each players skill level, tastes and experiences. The ROMs floating about online are devoid of this AI since they only existed in the original cartridges.

This AI could change something as basic as enemy placement, but it could even swap out star objectives and levels. It would only shift existing assets around though, it can’t create anything new off its own accord.

The AI would then manifest itself in what is called the internal plexus. The layout of Peach’s Castle is so bizarre an incosistent, its structure is just a mimic of the AI’s algorithm. In other words, the map of the castle is the blueprint of the algorithm.

Now, this is just an urban legend so there’s no evidence of it besides people’s foggy memories. Even the craziest of occurrences can be explained by glitches or ROM corruption.

What does that have to do with anything?

Well, these fan legends are the basis for B3313. The idea is that the doors, warp pipes etc can lead to seemingly random areas of the castle. This gives it a chaotic atmosphere that emphasises the horror-creepypasta mood that a possessed game is supposed to have.

B3313 Style and gameplay

The hack plays in a very similar structure to the classic SM64 – you play as Mario exploring the castle, going into paintings, collecting stars and fighting Bowser. Where it differs is everything else.


The plot is very ambiguous. The starting texts are all very matter-of-fact and instructional in their nature:

Welcome to Mario Wonderland. If you’re the adventurous sort, pay a visit to the castle ahead.

This castle is exclusive to the show. It’s connected to a variety of worlds, so open the doors ahead and get adventuring.

The story really takes place in the level design. The way the levels are structured and change over time, the way the enemies have been corrupted and so on. There’s even a shadowy figure (that I have yet to encounter) who is meant to represent… Something.

What are you doing up here? You should be looking for the princess! What, what do you expect, some lives? There’s no second chances.

– Yoshi, summing up the mood


The doors are all unlocked. This could be because of it still being in development, but it does make it a lot easier to explore the castle.

A lot of Mario’s moves have been modified – Ground pounding is faster, double jump is higher, triple jump makes you float, etc. Other times moves like the long jump are locked behind getting red stars.

Besides the main castle area, a lot of the stages in B3313 are based off of either SM64 urban legends, rumours and even unreleased beta content. Most of the stages are pretty short in the sense that there is only one star amidst an otherwise empty stage which does make the game seem a lot more fast-paced.

The audio in the game is pretty interesting. Some of it is the same as in the original game, but most of the other time it’s original or an off-key version of a classic theme, making it all the more eerie. Even Mario’s voice has become strangely realistic.

Overall, the idea of the ROM is to make you feel uncomfortable. This can be either by providing an atmospheric horror or by distorting familiar elements until they end up deep in the uncanny valley.

Conclusion and review

I really like the concept behind B3313. It does somewhat remind me of Another Princess is in our Castle except a bit more surreal and abstract in the way it interprets Peach’s Castle as a setting for horror. The familiarity of the castle alongside the differences and unpredictable behaviour really helps to create a dream-like environment that keeps you on your toes.

The scope of this mod is enormous. There isn’t exactly a precise star count since there are some duplicates and some inaccessible levels, but it is estimated that there are around 140 of them in total. That is quite a bit more than the original game, making sure that there is always something new to explore and discover. This could be a disadvantage though since the large size of the mod could have been a bit too large and difficult to complete, causing a lot of scope creep and complexity. This also makes it the largest mod out there, at a whopping 98MB – much more than the N64 console can handle.

Something I found very difficult to contend with were the controls. There is a bug (or feature) where Mario just veers off to the side. In the footage above it looks like I’m playing pretty badly, but sometimes I’m heading towards a cliff about to fall so I try to move towards one side to safety but the controller just steers me towards the right. This doesn’t happen in the other emulated SM64 titles, so I’m not sure why it happens here.

The other issue is the camera. It stays at the same level as Mario all the time, which messes up with depth perception. In some cases like the two screenshots on the bottom, you can’t even see where it is safe to jump. You just have to take a leap of faith and hope for the best.

Overall, it is a shame that the project was put on an indefinite hiatus. I believe that with a bit of polish, this could have been a great remake with an original concept. In the few runs that I’ve done (and some videos that other people have made), the game does appear to be identical. So the “personalisation AI” is really just a plot point and not something that was actually implemented. It would be interesting if the game generated a seed upon file creation that decided what the castle structure was by using a procedural/roguelike algorithm.

There’s a fairly good wiki that tells a lot about the project, and I recommend you check it out since it does give a lot more backstory on both the creators and behind-the-scenes.

Articles across the web

B3313 is a hack of Super Mario 64 that follows the urban legend of the personalisation AI and internal plexus theory made by ChrisRLillo.
Article published on N64 Squid


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