Okay I played a few rounds, here are my thoughts:

• "Beschte Quali" fand ich witzig, trotzdem muss jeder wissen können, was die Option bedeutet.
• Visibility of asteroids is pretty low since they are blending into the background too much, consider making them brighter, and turning the vignette down by at least 75%, it does not need to be that dark at the edge.
• Sometimes you'll die just at the start of the game since asteroids spawn on top of you, make sure there are no asteroids spawning on the screen, this helps the visuals aswell
• I can technically just stay still with my rocket, but I think that is not really intended? Maneuvering it is instant aswell, which feels good, but makes the boost kind of useless, since I can just turn around instead of boosting through danger. If it were harder to turn, you could solve both of these problems.
• The Upgrade UI has parts that I did not see at all since they were dark aswell, consider adding  a background or making these elements white instead of black
• Does the game actually need a loading screen? A simple fade would probably suffice considering almost everything is instantiated during gameplay
• Also, check if you are building some unneccessary art or files, since 100 MB archived seems really big for a game this size 

Don't think I did not like it, I think it's a good concept and looks pretty cool (I liked the sun and how your screen looks just when the game is starting), just a little more polish and you got your hands on a pretty good game! Great job!