Hello, some good ideas i would like to give.
1. Make some kind of 'Upgrade System' so the players have something to work for, example: New tanks, speed upgrades, damage upgrade etc.
2. Add some challenge to the game example:
-Enemy shooting
-Add a health bar to you don't just get one tapped
-New levels
3. Get some friends and brainstorm some ideas to make the game better ''if they're interested''
Thats all i got to say overall the game would be amazing after some changes
Your a very talented person.