It basically does it by who is currently "closest" to winning the game. So before there are any mines that'll be the player with the most outposts. Once a few mines go down it'll be the guy with the most neptunium. It's like a snapshot of a results screen, if the game were to end at that moment, the person on top of the list would be the winner.
My faith has found a resting place,
Not in device or creed;
I trust the ever-living One,
His wounds for me shall plead.
I need no other argument,
I need no other plea,
It is enough that Jesus died,
And that He died for me.