Very nice game, I could see it expanded into a roguelike with procedurally generated maps and more fun powerups to explore.
Speaking of "expanding" the game, I have a couple of suggestions and feedback if you plan on work more on the game:
- Movement feels unintuitive with the A and D keys (or arrows) used to turn and the W key to go forward, maybe consider having an option to change the controls with, for example, moving onto the direction pointed by the mouse by pressing W or controlling movement in all directions by simply using WASD;
- Sometimes, my ship explodes from getting too close to red space objects but not touching them, especially when near the edges of the map.. I don't know if this only happens to me though.
- Blue objects are really hard to see on the minimap, maybe give them a brighter color since the dark blue does not have much contrast with the black background on the minimap.
- Consider either giving UI scaling options to the player or scaling up the UI for the upgrades menu, since it's hard to read on smaller screens (I played on a laptop, and the text was really small compared to the rest of the UI and texts).
- I don't think you should have blue resources respawn around planets (or blue asteroids?), since I can just circle a planet to get infinite resources and buy basically everything in the game, making the resource collection aspect less meaningful when I don't even have to explore the map to get new resources.
- Maybe consider making planets you colonize give you different powerups instead of needing to collect yellow elements on the map to upgrade them: this would give the "colonize" mechanic more impact in my opinion, plus it would make the game more exploration oriented if you plan on expanding the game (but in the end that's just a matter of preferences for you, and how you want to ultimately design your game).
Overall, this was a really fun experience, good job on that, and hit me up if you end up expanding the game further :D