Thank you for the feedback! There is no sound included yet. Unfortunately I use Linux as my main OS, and there are some issues with the Unity Editor: building a WebGL app causes all sound based extensions to be unreadable, therefore the build always fails. Looking forward to switch to Windows pretty soon :)
Also, thank you for the ideas! The game is kind of raw for now, and pretty boring, I admit. Making a specific target location for the tank to reach while being shot at, would make the game be closer to a Tower Defense genre. Also smaller levels with different patterns would indeed make it more fun and enjoyable.