I used to play it when I was about 10 (2002). It was an RTS game, that took place after a nuclear war. You could pretty much only build tanks but they were customisable. I can't seem to remember much more than the order in which you fight the enemies: first it's only scavengers, then you are attacked by Yellow then Gray and finally Black. Some missions were snatch and run missions where you didn't have a base, only a few units and a time limit.
Sorry but that's all I remember about it, would much like to play it again though so if anyone knows what I'm talking about it would be great! Cheers.
The only one I can think of from about that time is Command & Conquer, but that has been out since 1995 and sequels were made up to 2003 until EA got the boot in. (I hated that game. Not my cup of tea, and it pulled Westwood away from the Kyrandia games)