How do you unlock the RTS maps on the menu?
 

I never figured this one out, but how does one unlock the various RTS maps on the menu? I have finished a few and see my times, but they are not clickable. Do you have to finish it a certain number of times in the game before you can play it standalone?

You must first complete the previous available planetary battles to continue to next ones.
The lightblue ones are available to play, while gray colored are yet unavailable.