It would be nice to play without the second stone upgrade. Because you can't just rely on gathering millions of stone and trading for the other resources, you will have a more diverse economy with peasants gathering other things beside stone. Games would be more interesting, with meaningful choices to make regarding the economy. People might actually do stuff like upgrading mines - a game feature that is actually detrimental if used when the 2s upgrade is available; i.e, the player that does that is actually less efficient than the one which simply rally points all peasants on stone. So the game punishes you for using it's features ! In addition, it will be more rewarding to conquer an enemy's base, because you will be able to mine more precious resources (gold, iron, coal). Unused player locations will also become more attractive, adding another strategic dimension. As it is now, it's sort of like C&C, where you only have one resource; stone is literally more important than gold mines - not to speak of other resources. Any thoughts ?