Your interpretation of the theme was very clear and understandable, congratulations! The sound, environment, and characters were also well done.
The game was enjoyable; I played it for a long time. The zigzagging of the bullets and the aliens' kicks when they took damage were great.
But I couldn't figure out the objective of the game. Maybe I missed something, but as far as I understand, the goal of the game is to collect as many precious stones as possible, right?