Winning the war on terror

What do we mean by winning? Do we think that for us to win ISIS must be completely destroyed or would we accept ISIS no longer attacking targets in Europe as a win? Can the war on terror ever be considered a zero-sum game?

Sports like football and games like chess are sometimes thought of as zero-sum games, if you win your opponent loses, but often they aren’t. If you’re playing as part of a league then sometimes a draw is enough to get the points you want to go onto the next round or stage of the competition. Sometimes winning doesn’t mean winning.

I wonder if anything is truly a zero-sum game.