WAR ROOM
In War Room, you start out on an empty map with unit production buildings, versus one or two computer opponents. War room maps are much more open ended than campaign maps and subject to far more random AI factors and conditions, especially in the longer maps. There are two general strategies to use in war room maps. One is to use Sami and go for a quick base capture while still getting a perfect power score. The other is to use a strong CO like Max and slowly but effectively drive off the enemy, while cutting off their income stream. In some of the easier war room maps, both methods will work depending on what you feel like doing. In the harder war room maps you may be forced to use a certain CO.
The original 20 war room levels are back, and some of them face you off against new COs. There are also 10 new war room maps. The difficulty of the maps can vary from easy to really damn difficult, although mostly easy. In the harder maps you will have to figure out special strategies to make it through. The tough war room maps stand out on their own in Advance Wars, having difficult technique and power requirements while still having you survive crippling conditions with waves of enemies and finishing in a timely manner. Getting perfect scores on these maps are also much harder because of the unpredictable AI. Some maps are so difficult that you will have to try the same strategy several times to squeak by with a perfect score.