Just a suggestion: Different weather types? In rainy weather there would be a lot of wind, and rain (pushes the shot down). In sunny weather there would not be any worsening things. In foggy weather you wouldn't be able to see the enemy tanks too well... etc.
Objective-based gameplay? Like, CTF:
Other team has earthquakes, and other team Diggers. The team with the Earthquakes would try to get the flag in the end of the map, and bring it back. The Digger team would try to prevent them for getting the flag. There would be 2 rounds. The winning team would be the one, who got the flag home quickest (less turns).
Add a possibility to add more enemies in the Firing Range, up to 3 enemies. I would like to train the shots on large groups of enemies. Also, to be able to move the enemy, would be a nice thing.
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