Questionable Questing

I just think it'd be neat to combine this with "simultaneous isekai", where every instance of the MC is basically like one character on the same account, so what they can share are basically what they get from achievements or account shared items, but not individual items or shit like that, and it's like every characters in a different world/server

That sounds like a pretty nice concept.

Yeah, I got really into it, the whole "everyone thinks this is just how the world is and only you know this is mechanics of a video game" thing is great, but there's this arc where they arrive at this "painted skin ghost city", you know there's a kind of Chinese ghost that takes people's faces and when they wear it, they become that person

So basically like half the city is actually made up of ghosts that stole the place of actual humans, but they basically behave just like humans, and one painted skin ghost fell in love with the MC, but the MC is like 'I can see your name in red and health bar right there', and eventually they find out the truth

So there's a drunkard gambler who wanted to sell children to pay off gambling debt and kept kidnapping homeless kids, and one time he accidentally killed the victim, and he dug a hole to hide the body, and he accidentally struck the entrance of an underground dungeon, and those painted skin ghosts leaked out from the dungeon, so when they want to "return to the underworld during chinese halloween",

it's actually "they want to despawn" because they've been out of place for too long, and gained too much consciousness compared to their natural state, so it wasn't some sinister scheme to invade the human world by monsters, but they were also victims that couldn't die