Ok so what you have to do is choose a way to kill the person above you. You can also choose a defense to use, then the next person has to kill you in a way that beats your defense.
EXAMPLE: player 1-i use a nuclear bomb and a bullet proof vest player 2-i shoot you in the face and use a forcefield player 1-i use an EMP and a fortress
but since those dont exist in the real world, you are defenceless. i then proceed to beat you down with a golf club. good day to you sir.
my defence is nuke proof bunker in the middle of the earth that somehow isnt boiling inside and has enough food/water/compressed air to last me a long time.