In what way does your game fit the theme?
In the game, you can unlock turrets that can increase your power, as there will be more bullets that will knock down enemies. Eventually, you can latch onto a turret, which makes you fire that turret's bullets with a better fire rate, bullet size, and bullet damage. If you're with your turrets, or attached to them, you are stronger.

Did you write all the code yourself and made all the assets from scratch?
Yes