Ok so maybe my mind is remebering things wrong...
But I am sure it's a mixture of the following...
The landscape (hills/ground etc) looked like the following picture:
The tanks looked like the tanks in this next picture:
And I can remember the colours and screen looking like the following picture:
As for the weapons menu, it was either like the 2nd picture or the following picture:
The picture closest to the game I remember is the 2nd picture, for the exception it was all in black and white(the mac I used didn't have colour...), because when you took your shot, you would see a black line/trail of your shot until it hit the target/blew up, just like in the 2nd picture, and I remember having different types of shots, like impact shots, shower shots, mortars, bombs that roll down the hill and hit etc...
Edit: I could have SWORN the game was called "Battletanks", and I strongly believe that because I remember a 3D arcade game in early 2000's called "Battletanks" and I was like, OMG THAT REMINDS ME OF BATTLETANKS ON THE MACINTOSH!!! And that's before I started heavily smoking weed...