Somewhat good game:)
It's a good game concept that can be improved of course.
Iwould suggest you to change tank's specifications regarding to Height. They would be a 3rd of the height you mention (to improve the specs which is a nice detail) and also, considering they're large tanks, well, increase the wieght of them as well.
Real tank guns shoot their rounds at very high speeds ranging fom 600 m/s to even more than 1.8km/s. This game uses a ballistic calculator of course so maybe you could try to escalate thuis in order to increase a bit realism. Also, low caliber guns have usually high reload speeds which range approximately between 200 rpm to even 500 rpm. Not to mention Gatlin type multibarrel guns like the Western 20mm Goalkeeper with 5,000-5,500 rpm or the Russian 30mm Kashtan which is around 6000 rpm. These values of course would make a game like this too easy and boring and would damage its style a bit, but you can take them as reference for to improve a bit shooting rate and precission.
One of the tanks looks deffinitely like an AAA system and also its caliber fits, I sugest you to give it a bigger reload rate.
And maybe you could add as upgrades different weapons like a Gatlin typed multibarrel gun which would expend its ammo quickly, but could be very useful against a boss (considering the gameplay features).
A summary, increase a bit reload rates, make specs a bit more realistic :) (a tank 3m wide and 12m high would look like a giant armoured ad rather than a tank :P), add some more kind of upgrades and increase the ammo's speed :)
I must say you put a good effort on this, so keep up the good job :) There's always space for improvement.
