it is possible to make my multiplayer game? I wonder if I make a rpg style game with exploration, times, people come out according to the time and that, I understand?

No never is anything is impossible as long as you BELIEVE!!!!!!!!!!!!!!!!!!!!!!!!!!!

There was a very old thread on this, but I don't think it ever went anywhere... I think the main problem is just with networking itself. Maybe if you're really knowledgeable with networking, you can make quest MP, but that means you got to be able to synchronize (the classic issues of "lag" and "desyncing" and "mis-matched game states amongst players / OOS: out of sync --- bug crashing errors" that are all too common in MP games, as that's the nature/issues with networking/MP'ing games) it for everyone (requiring great knowledge of networking) and of quest too, in how to turn it into a MP game (quest knowledge + networking knowledge).

So, it's presumably possible... but has anyone done it... not as far as I'm aware of, anyways.

if you mean within the game itself as it (quest) currently is (SP: non-MP --- discussion)... you can ONLY control one Player Object at a time (although you can have/create the effect/illusion/functionality of controlling an entire party/team like many RPGs, with scripting and fancy coding design/ability/etc), but you can switch between Player Objects using the 'ChangePov' Function. The Lost Vikings 1+2 (SNES) game is a good example of controlling only a single character at a time, but being able to switch between (3 specialized/unique abilitied) characters, though as a side-scroller, but the concept is the same, whether it's a side-scroller or a text adventure.

This is the most recent thread about it: https://textadventures.co.uk/forum/samples/topic/4013/online-multiplayer-w-node-js

You need to set up a nodejs server somewhere. It's not designed to be peer-to-peer.