Step 1
With notepad or another text editor create a file named exactly steam_appid.txt
Step 2
Put only the number below in that file and save it.
366220
Step 3
Copy or Move that file into this directory ... \steamapps\common\Wurm Unlimited\WurmLauncher
Step 4
Now run Wurm from a shortcut for the (WurmLauncher.exe) executable that is in
the same directory as the previous step.
Step 5
When you run the Wurm Client, input whatever name you want your alt to have in
the upper right of the launcher client.
Below that there is a dropdown option, that allows you to have different settings
for the alt, so you could have it use less system resources than your main.