Oo, I have the previous two Wargames but not Red Dragon. Fascinating WW3 RTS with a deep emphasis on simulation. Very complicated and difficult, but satisfying as all heck. Brilliant combined arms tactics and a solid interface to give you a shot at managing it all. It has something like 800 different units spread across a bunch of nations, and kind of does want you to care about the differences between them and their role on the battlefield.
Would be a really fun comp stomp game with some friends, which it being free makes rather more feasible.