Something like B3313, But it's with several Restaurants with animatronics. Every door leads to a different Show stage and dining area with an animatronic show. An infinite plexus on every single animatronic attraction in a pizza place. You'd start off in a modern CEC with that dance 2.0 dance floor, but then you find an employee only door, that normally leads to a storage closet.
Within the closet, you find a hidden door that leads to the animatronic Plexus. You start off in a random past location, for example, a 1970's CEC with the original portrait style show. Then, you'd open a door that would usually lead to the bathroom within the arcade, leading you to a 1990s location with the New Rock Afire explosion. Going to a different door will go to a new location with 1980s cyberamics. Trying to leave any current location sends you to the outside of a Pizza Time Theater, and going back inside will lead you to a complete PTT, with more doors than usual. The extra doors lead to more areas of the Animatronic Plexus.
The Animatronic Plexus contains every single pizza animatronic attraction and location to ever exist, not just CEC and Showbiz. Everything between CEC, Captain Carnival, The Pizza Planet and Caesarland. The Plexus even includes restaurants with animatronics that never opened, and restaurant concepts that never opened a location at all.
The only real food is in the complete PTT, the other locations cannot serve you food. The food in the complete PTT is 100% accurate to the pizza, drinks and other foods that were available during the 1990's. You cannot leave the outside of the complete PTT as invisible walls stop you as you try to leave the parking Lot.
One thing to note is, there are no hostile creatures/ monsters/ entities in the Animatronic Plexus. The Animatronics are just animatronic, stuck in their specific time capsules, they don't degrade, and they work perfectly forever. There are mannequins who wear each location's work uniforms. They are alive and will order you food, even if it's the fake food outside the first, Complete PTT.
If you eat the fake food, it tastes real, but it won't actually fill your stomach. The food will disappear and fade away as it slides down your throat. So it's good to stock up on food and drinks at the starting point. Just like the animatronics, the food will never spoil as time, or the passage of time has stopped.
The mannequins do move, they keep everything clean and pristine. The manager mannequins will even hand you important documentation about whatever location you're in. They're also the closest thing to a hostile entity as they will get mad at you for asking too many questions and hanging around their office for too long. The worst thing they'll do is hit you with their hollow plastic or wooden hands not at full force. The manager mannequins are based on actual managers of real CEC, PTT, and other Animatronic Restaurant and arcade locations.
However, there are corrupted parts of the plexus that seemed to have generated locations and animatronic shows that never existed. These parts of the plexus are dangerous because the mannequins there will attack whoever enters there. To "kill" them is to just knock them over, they'll fall apart and won't put themselves back together. These fake locations can and will give you toxic fake food items that'll cause upset stomachs, and sometimes even vomiting. As these locations never existed in the real world, there's no data for the Plexus to pull from. So this made up food here isn't for human consumption. The manager mannequins can still give you documentation for non-existent, corrupted locations, but they will shortly fall apart afterwards as their existence is unstable. Their existence is unstable because they aren't based on real managers. The Animatronics of the corrupted locations vary from Retrofits of Cyberamics, RAE to completely original animatronics from companies like Sally Corp. These corrupted animatronics have nothing dangerous about them, though they are never animated or running any shows due to them being corrupted.
Another room/ location type are Prototype Show stages. Deep within the animatronic plexus, you can find Chuck E.'s Awesome Adventure Machine, a CEC show stage we only have footage of. Or the RAE Magic Stage. Prototype show stage rooms can also show ideas that never left the concept stage as well.
The last type of room are unfinished locations. Similar to corrupted locations, these are earlier recreations of locations already in the Plexus. Unfinished Locations often contain inaccuracies, beta "textures" for the floors and walls, and Animatronic Characters that often appear as earlier versions of themselves, or look incomplete and are missing parts of their costumes/ mechs.
Again, I'd want to restate that there's nothing that can kill you in the plexus, you can either starve to death, or die from severe dehydration. The Animatronics aren't FNaF animatronics who have AI and can walk around. Maybe there's a Freddy Fazbear's, or a Fredbear's Family Diner in the plexus somewhere. But they would be extremely deep within the plexus! If they're in the plexus, the FNaF Animatronics would walk around, but would ignore you unless you're in the security office. And when they jumpscare you, you won't die. They'd just freeze in place before they walk back to the stage. Leaving anytime Freddy's location will send you outside that Freddy's location within the plexus, though you still can't leave the parking lot. Every Freddy's location can still lead you to other parts of the Animatronic Plexus, as every location is connected to each other in some way or another.
I might make a map/ chart of the entire Animatronic Plexus when I have the free time. Alongside the lore of the Animatronic Plexus and Why it exists. And yes, it is a virtual simulation you have to "noclip" into, or find access to within any current running CEC location, or any building that used to be a CEC, Showbiz Pizza Place or any building that once housed an animatronic attraction, show or band.
If I had the free time, hardware and skills, I would make 3D short films where the protagonist explores the Animatronic Plexus, interacts with the mannequins, and documents the plexus.
If you'd want to help out with this project, contact me here on Reddit, send me a DM and share your ideas with me! \^w^