Zero sum game is a situation in which a participant's gain or loss is exactly balanced by the losses or gains of the other participants. Thus cutting a cake, where taking a larger piece reduces the amount of cake available for others, is a zero-sum game if all participants value each unit of cake equally.
Is such a deal halal? Or is it considered as harming other(s)? What if all participants agree and satisfy with the deal, would that make any change?