No mater how you do it if its the .ZIP or the Installer its going to write to them folders. Saved games will be put in the Steam folder in the AppData area.
Doesn't this help?

What I found is copy#2 had ERRORS and wouldn't run on the port 34197 when copy #1 was running. The program needed to see ...

3. Play alone, you are not player #1 anymore.
The only place this will matter is poorly coded mods / console commands

The steps can be greatly simplified, just download the .zip version from factorio.com. This version will use the read and write paths where it is extracted too.

It isn't ...

camelCase wrote:Is it possible to run multiple instances of factorio to test mod development in multiplayer?

YES!.. I show it in my post..

kds71 wrote:Not on one machine. I have a desktop and a laptop so it makes testing multiplayer possible, but if you are limited to one machine you should try virtualization: https://www.virtualbox.org/

Yes you can do it on one system!


Virtualbox is a HUGE waist of your system and you DO NOT NEED IT..

Running multiple instances of Factorio???


You should read threw this post before starting this.


One is steam
The other is to download Alpha version (you will need to have a steam account and link it so you can download it from there page at Factorio.com)

Install Stream first.
then
Install ...