The idea is super simple, and the game actually okay fun to play. Some music and/or sound effects would have made the game even better.

Wow, this is actually a really fun game!

Sadly there is a bug, where starting the game instantly colors the starting planet red, so in order to play it, I had to start it about 10 times till I was able to really play. Could it be that the speed of the game depens on the number of frames? Because, everytime that happened, the console printed a very high amount of frames, about 1000 (and maybe you should remove the fps counter in the game). If that is the case, then you should change the game to take the time between the frames (often called delta time) into consideration when updating your game.

Also a restart button would be great!

Oups, forgot that the source code is accessible, maybe I'll take a look into it.

I just want to add, that randomly placing the planets would be cool.

Also, LINUX FTW:heart:!

Thank you for your feedback. I've tried to do the things you mentioned (random planets, non-fps dependent gameplay), but I ran out of time before I got to them. LINUX IS BEST!

Solid design!
Obviously more visuals and audio would've made it better, but that's more of a time constraint.
The fundamental design, however, is SOLID.

Simple fun is the best fun, especially for LD. Good job :D