in a minimalistic environment, we can only wait for user input and then print result on a roll of paper.
But non-blocking socket, while complicated, not impossible and portable though.
Same goes with threading. 
In most programming language accross operating system, without any support library, you can assume blocking input, cursor-less print, tcp/udp socket and threading.

In this constraint, we can build a console Multiplayer Interactive Fiction.
but, by the time between [enter] stroke, the world is changing, other players press [enter] too
this yield a game where you can get robbed thing from our hand while you are stairing at it without actually realise you dont have it anymore.
A mmo of dude stairing like mental lunatic. 

This is an exemple of hardware constraint based game mecanic design.
The key concept is everyone is either absent minded doing something like staring and changing its activity based on his realisation of the situation.
that concept accepted, you have a MMO

consider the world as if your player can only interact with the world using a timefreeze watch
all player will live in their own paralelle world and no one will be able to interact.
they will leave note for other player to read and they will leave back the note.
any aggression will be felt later so it is impossible to dodge any violence.
economy could be based on thievery, each turn, everyone steal back.
a weeping angel game in doctor who universe will look like this.




where is the fun?
reading is fun, reading interactively can be funnyer. This is why internet have more social media than anything else.
MMO is social media packed into a game. 

ok what do you plan to make the game fun?
it will be an orgy, every can fuck each other in ther own time space, so you will always feel butthurted
you will start every turn pranked by all other people in the room
it is a party where you go room to room and fuck every body