Primary Challenge - Make a scene where your characters find something. This can be anything from an ancient artifact, to a new type of mineral, to the location of some secret plans. The challenge should focus on the subject.

Secondary Challenge - Make a scene from an alien planet. This should have elements in it that are noticeably different from where you'd find humans living today. Some ideas include an underwater setting, different colored terrain, or plant life that seems other worldly.

I decided to eliminate the Secondary Challenge B. There are still 2 free builds per month.

I finally have time to look at these; there's definitely some planning to do :o)