Nice work! Simple to understand and play, but it feels like managing a space empire. Cool music too.
On the first level I didn't notice there were more worlds off the top of my screen until the AI came to conquer me. Later I found that flying to as many worlds as possible as soon as possible is the way to win - and the AI could never catch up after that. So, really, the tutorial level was the hardest!
The game window is a little too tall for my screen - my tiny laptop is only 738px high, so I had to constantly scroll up to see the resources I had and then down to spend them.