No. In average utilitarianism, you take the difference and divide by the number of people. The method this game uses would imply that doubling the amount of pleasure and pain each person feels would have no net benefit or cost, regardless of what the original values were. If there were only pleasure, it wouldn't matter how much, so long as it's greater than zero.

Also, if you used this method, and there were lots of other people in the world, it would effectively come out to the same as normal utilitarianism.