oh, this is a great question!! i've thought a lot about it, actually!! nothing super conclusive, because i really love theorycrafting and making up mechanics and puzzles like this (and id love to hear what other people have to say too!!), but i do think there would definitely be some time related puzzles involved. theres actually two i initially first thought of; reoccuring rooms or floors is one, where they repeat indefinitely and are all completely identical to each other, save for some minor differences, and they would repeat and repeat until you find your way out. it would serve as a stage for information gathering puzzles and possibly story related segments, as it relates to the second idea i had; parts of the palace where, upon entering, some of the PT's lose their thieves attire. for example, if the PT's were to enter one of these rooms, say, closer and luce would revert back to motoha and shoki. it isnt that they no longer have their personas, but that these rooms exist outside of "real" time, and inside, those thieves weren't real phantom thieves in the time period the room is set in. i think itd be a cool setting for challenge bosses and story related segments.

thats brilliant. thats hilarious. you guys are so much better at this than me.

i'm so glad!! the fandom is really small, but i absolutely love seeing what everyone is coming up with, so i understand your position... i love talking about this AU too so more will come eventually.!!!

i love answering questions too, so of course you can ask! i didn't actually consider the cognitive thieves hating him, but that's such a good idea, especially considering how guiltridden he is... as it is, the cognitive thieves are probably the same if not more forgiving than in the real world. nagisa knows full well - to his own anger, really - that they would forgive him instantly if he were to ever tell them about how he's failed them. they're very protective of him, but he feels really guilty about it, so his shadow is always just observing from afar or has locked himself away in his quarters.

i could very easily imagine them being antagonistic towards the real thieves though... maybe the severity of it on a case by case basis. like, i could easily see cognitions of masaki, seiji, leo, or yukimi, etc being very defensive for example, whereas others like tomoko, miyu, or chizuko, etc would probably want to encourage outside help, since they know they can't do anything for him, otherwise something would have already changed. some of the cognitions are very out of the way - kira is always in the infirmiry, for example, or kiyoshi in the library - so their behavior would be up to how you'd approach them as well... the actual average shadow on the Ark is really hostile though, since its basically their 'grave'.

shadow nagisa's attacks are actually kind of similar! though he typically resorts to just fighting with his bare hands LOL... he has a knife he stole from the real nagisa, and his gun, the bullets able to change elemental affinity based on nagisa's own whims. shadow nagisa is actually pretty defenseless, and its by design, but he's also very volatile and viscious when he doesn't get what he wants, even if he doesn't actually have any real intent to hurt anyone. heres a snippet from a fic i haven't published yet:

He stretched out his wrist, circling it as he fixed the sleeve of his shirt. “You’re right,” he said. The breathlessness of his voice made them all step back, shivers running up and down Shun’s spine. “None of you have it in you to kill me. But I can make you.”

Before either of them could even think about what that meant, Nagisa was running forward, boots slamming against the ground with enough force to launch himself at the three of them.