Ya got me there! I should've caught the dunes before, but unfortunately I didn't. As for the spaceports, if you can believe this I just now realized that the settlements were Isometric as well! I've looked at that map probably a good five-six times and just now saw that those suckers are isometric domed cities. The spaceport design makes more sense, to be sure, with that thought in mind. I think that's the catch for me, the spaceports seem to vividly stand out.
As far as the board game, I'll have to give it a look to be sure. Looking at a few quick sites I found online, I have to say that I like your map better than theirs! They really didn't have a very good color scheme or design, it seems so flat. I think I'd rather take your map if I ever give it a shot.