An old game called Warzone 2100, it's an RTS with a twist - you design all the units yourself, and there is a massive tech tree to work through. It's got quite a fun singleplayer campaign. For myself, what I always enjoyed was trying to keep ALL my units alive... for the ENTIRE campaign. This way they become stronger, and you get a sense of continuity through the campaign.
Anyway the source code was released or something so some guys went and remade the entire thing as a free standalone install. I *THINK* this is the right URL.
[http://wz2100.net/][/quote
I tried downloading it and all it does is give me a screen on three trucks and a searchlight(?). A bit disappointing since it piqued my interest, but I'll keep trying. (Plus with my lack of expendable cash, free is good. Part of the reason I'm trying to get into PC gaming now along with my consoles.)