Best campaign engine I've ever seen in a game, the beauty of it is that all events are handled statistically until they are in your vicinity, allowing it to handle more than 50000 units in real time...
(Tip: always try to cut the enemy lines of advance at the begining of the campaign, blow up as many bridges as you can,ignore the mission objectives, it'll be less score, but it'll help you to win the war.)
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