Game opened in the middle of my two monitors instead of the middle of my main monitor. Toggling Fullscreen option fixed it.
The crosshairs are very thick because they're low resolution; they block a lot of your view.
The tank seem really fast, I hope you can drive stronger, slower tanks in the final version.
Really neat you have a replay mode.
Someone recently released this godot addon which might interest you: https://github.com/cloudofoz/godot-smashthemesh