Single player co-op?

just wondering, if the world you’re playing on is consistent between characters, is it then possible to run several instances of the game at a time, thus effectively creating single player co-op? and if that works, how much of a leap is it to full up multiplayer?

i used to play a game called EUO:
http://euotopia.com/

the dev’s name is EggMceye on the forums:
http://forums.swut.net/

the game runs pretty well, and it seems to me that Cataclysm is much more simple, sooo…

A constantly updated world, but without actually seeing anyone and having everything looted.

Basically an SSH servers.

if you use the same world the items stay. however, spawns are separate for each so are corpses. I have 2 different types of starts going in .71 and they both ended up in the same shelter. so they share items. could lead to interesting ideas for sharing generated worlds.

How would the game handle turns? Would both players “choose a move” then lock it in and it plays out, like in a turn based strategy, or turns happen automatically every so often? Anyway, this is a great idea I think. I would love playing Cataclysm with my friends.