A while back I decided to do a little research on the gameplay/concept art from Mars and believe that the playable area on Mars may be located in the Tharsis region. As you can see in the image linked, there are several clues that reveal more about the location of each picture: the ruined old station is named "Pavonis station" and if you look [i]really[/i] closely the sign behind the Warlock says "Tharsis junction". According to wikipedia, Tharsis is the name for a huge volcanic plateau centered near the equator in the western hemisphere of Mars and is home to some of the largest volcanoes in the solar system. 'Pavonis' being Pavonis Mons, a large shield volcano located in the Tharsis region. It is the middle member of 3 volcanic mountains, collectively known as the "Tharsis Montes". There are even some who think that they entire region may be one giant volcano. So with all of this in mind, it definitely seems that we'll be either in or around the Tharsis region. We should get a rather nice view of Olympus Mons, the second tallest mountain in the solar system. So, when we finally get to Mars, be sure to bring your best hiking boots... :)