This is a fantastic game for all ages. I rated 12+ because it is still a war-based game. However, it also makes you think and teaches you how to handle resources.
It is hard to say how violent it actually is, because all of the fighting takes place amongst robotic machines controlled by a human commander in a large bipedal walker called an ACU (Armoured Commande Unit). However, the violence does consist of robotic tanks, bombers, walkers, and navy being blown up, smashed and utterly destroyed.
It is a great game though, and well worth playing. If you are interested in it, check out the sequel.