Far from being a desolate, lifeless red desert, Marz is teaming with life – UNDERGROUND. Marzians mostly occupy and work in five vast subterranean layers that cover many tens of thousand of your square miles (or kilometers).
Layer One is nearest the surface. All the main Spaceports (Including MASA HQ) are located here as well as the many secure exits to the surface.
Layer Two is where most Marzians live and socialize, hence this layer possesses the largest population.
Layer Three is dedicated almost exclusively to outdoor sports and leisure activities such as sailing / skiing / swimming and a hundred other hobbies. Weird, right?
Layer Four is where Marzians go to work, and where you will find the factories and research labs that fuel the Marzian economy.
Layer Five is very ‘hush-hush’. Only those Marzians with the highest security clearance are allowed to visit this strange area. It's where the most cutting-edge technology is developed (or so the Marzian authorities like people to believe).
At the centre of Marz is the internal ocean called The Great Open Seaz. A must go to vacation location, this vast expanse of water contains creatures that no humanz have ever seen, and is a magnet for those Marzians who love to ‘get wet and wild.’
Connecting all of these layers are the hyperlifts. Marvelous pieces of tech, in principle they are similar to one of your ‘elevators’. Simply state your destination and enjoy the (very short) ride. Seconds later upon exiting you may find yourself thousands of Urth miles from where you started.
Some Marzians swear on their mothers' antennas that dozens of other layers exist, but are kept secret because the ‘government’ does not want overly curious kids (aka conspiracy theorists) snooping round. This is the legendary ‘Dark Zone’ of Marz. This massive region (both above and below ground) is off-limits to most Marzians and left untouched. Roswell much?