When i first got hook on computers it was at my day care as a kid and on the 98 computer they had a number of demos, starcraft, bonkheads, Caesar III, etc etc

There was one game, isometric top down and was an alien game and if I remember right you played as the space craft and the bad guys were the farmers with shot guns and there were crop circles in different fields. the graphics in terms of level of quality, at least in my memory weren't all the different from Caesar 3.

thats all i remember