You're confusing yourself because you're mixing scoring systems -- first you say that the game is zero sum, win or lose, then you talk about variable sum game resources. In a zero sum game, the total score is always the same; you can either steal points or give them away, but can never destroy them. If the total score changes throughout the game, then you're not talking about a zero sum game. There's no different levels, though you can play a zero sum game as a variable sum game (I won while at full health!).