I like the graphics, and the damage animations we're getting on the ship :) It's well modeled. It's cool that you thought of putting an option to reverse the axis!
Some ideas to improve the game if you decide to made an update :
- it would be interesting to add an indicator to our goal
- add lights to the ship to make it easier to see
- try to implement a speed sensation by scrolling the background
- turn down the sound of the shots and explosions a little, add a background music
- maybe add items to get bonuses like a new shooting mode for example
Anyway, having managed to do all this by yourself is really great. Good job =D