Scorched Earth was a multi-player PC game that was popular in the early 90's. The basic premise was you controlled a piece of artillery, on a 2D destructible landscape, mostly mountains. Your opponents were scatted around the board as well. You all took turns shooting each other with a variety of weapons. The challenge was to line up the correct angles to actually hit your target.
I remember me and a bunch of grade school friends getting playing this at a friends house. it seemed pretty amazing then, and it was a lot of fun. There were some pretty big weapons that you could purchase, which took out a large chunk of the landscape. MIRV, a warhead which separated into multiple warheads (3 I think), was always fun as well.
The reason this game came to mind is that a real-time Scorched Earth is coming to X-Box Live, called Death Tank. This game was actually on the Sega Saturn, an Easter egg in Duke Nukem 3d. They have upgraded it a lot for the X-Box hardware. The old version was turn based, so we will have to see how this one goes. I will likely download the demo at least. Check out a gameplay video:
Death Tank XBLA from Rlan on Vimeo.