Fun game, I've got some suggestion/balancing on how the game could be improved in my opinion:
-Make the tank shells go faster to increase effective range
- The 90mm gun is fun to use but way to inconvenient. Give it more elevation, like 40° to use it as an artillery and give it like 5°-10° of deviation to allow for more precise shots and the explosion radius is pretty inconsistent, sometimes the explosion make seems like there is a hit but the enemy is just fine
- Buff the rockets, make them explose on impact only and not detonate automatically at a certain range
- Make the flamer shoot when you press space like the chain gun for better practicality
- The shots don't go exactly where the crosshair is, it's particulary visible on the railgun
-Give more depression to all gun to allow more verticality
- Add some ability you can choose like invisibility, making your tank jump, superspeed etc for your tank, to balance things up you can make them drain your shield to work
- Make infantery more deadly by making them throw antitank grenades if you are too close
- Add some enemy artillery tanks or position that will shoot you if you are spotted to avoid the player being too static
- Add custom shells for your tank like AP for better pen, lower damage, APHE (current shells in all guns it looks like), High Explosive and even HEAT as a last strongest shell you can unlock that is technically HE+AP
- Add more objective like, defend a point, capture points
- New gun ideas : Rockets (like a katucha), TOW-missiles, heavy autocanon like a bofors, twin autocannon, gatling autocanon, 75 mm cannon to make your tank a small tank-destroyer like a marder III
New hull ideas : A grenade launcher, a spear head to ram other tanks, a mine launcher
- Finally, explore more options for your tank customisation like maybe add new hulls, turrets (maybe multiple turrets), some possibility to add more armor or some plates to add more protections with stats so players can choose their playstyle more as somebody would make a full speed, big gun gobelin and some make a slow and sturdy foretress.
I've stopped playing at level 4, maybe you added some of the things I suggested here, keep going and good luck