This is an empty field and we are both running fence to see who can get the most. The stones are the fenceposts and you fill in the fence when you get pushed. To keep it interesting (and not turn into "My side, your side") you can pull out the posts if you surround them yourself.
Imagine the line segments leading away from your stones to be straws through which you can breathe. If you have no more open straws, then you die.