I have to say I have experienced some odd tactics from NC on Miller since release, for example: all the NC attacking Eisa Tech Plant at one point...
If you don't want to give it admin access to install an update then you're not gonna be able to play. All programs that install to program...
Click no on the UAC popup when launching it from steam, then the steam overlay will work. If the game needs to patch then you'll need to click yes...
If you press no it just means the game won't patch (because it doesn't have admin rights to the file location), but the game will run fine. :)
Separate names with a comma.