War is a physical struggle for something material (territory), it is not a contest where the winner is awarded a prize.
It is assuming the characteristics of a contest, especially for wars fought in times of abundance.
Roman and Persian generals would scratch their heads at the precision with which we try to avoid collateral damage, and even soldiers on the field nowadays have a band on their arm identifiying which team are they with (it's yellow for Ukraine and Red for Russia).
Even going back to the days of Kosovo and Bosnia that was unfathomable.
Who is the “you” that can establish and enforce this?
If such a party exists, they have the power to defeat either of the nominal parties in war, and the ability to dictate results to them, and obviously they care enough about avoiding war to dedicate the resources to enforcing a resolution, so they have already rendered the war unnecessary: why would they not just decide the result and enforce that decision rather than letting a videogame do the deciding for them?