I have a couple of the Legos Mars Mission sets at home. I actually built two of the large kits in one day. I was excited to find out that Legos also has a Mars Mission on their web site. Of course you are going to need the access code to play. I found these codes on a web site: manic, match, santa, temple, checkmate, pizza, and maze.
I was also told that there are some other codes out there, if you know of one, please post it in the comments area.