maybe a system where you can level up your tanks, and give them armor, the damage you take is reduced by up to 50% maximum, and upgrading would cost coins. This would actually add a lot of cool customization to tanks, and maybe missile trails too.
Another feature that would be cool would be if elite crates fell from the sky, with an announcement at the top of the map (highest point at that moment), "Elite Crate Dropping" which gives you some special reward to customize your tank further, like a hat or something
also pls add lasers those things would be so cool
and maybe adding 50 more levels for new weapon unlocks would be cool :)