I remember playing a worms-like game but can't seem to find it.
Two tanks (bases perhaps?) had to take turns shooting at each other. When you won a round you got money to buy new types of ammo. I recall it was a pretty extensive list. As far as I remember the tanks couldn't move.
Maybe "Scorched Earth"?
http://en.wikipedia.org/wiki/Scorched_Earth_%28video_game%29
I had loads of fun with that one!
It could be any one of the old Artillery clones [1]
The one I played the most was Tank Wars:
[1] http://en.wikipedia.org/wiki/Chronology_of_Artillery_video_games