People scream when they die. They scream even louder when they burst into flames. There's the ominous hummmmmm of the Nod Obelisk of Light as it charges its laser cannon, and they captured the sound of the 7.62mm chaingun beautifully. And then, of course, there's that sexy voice of the female narrator during battle. The individual units have great animation.
Infantry stop and clean their weapons when idle.
That little turret on the Humm-vee swivels to track its target. The radar dish on the communications building turns 'round and 'round. When tanks turn, the turret and body rotate independently. And the men run around screaming when attacked by flamethrowers. It's art, man.