Nice that so many users played the game in the end! This is my personal favorite of the jam. Graphics and mood are stellar. The only real room for improvement I see is adding features to the gameplay. After winning 1~2 times I feel like there is no more place to improve my playstyle.
One thing I could imagine is some kind of defensive maneuver. When playing I never looked at my own city as I couldn't do anything about it anyway. When there would exist e.g. a shield that you could activate you could lookout for incoming missiles to detect against them.
This is not meant as critic but just as a pointer what could be added if you wanted to. For the short time it's an excellent game.