How do you unlock the RTS maps on the menu?

[ywenli]

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?

[Vertix]

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.