[tratclif]

My copy of GURPS Mars has gone wandering, but the Dying Mars chapter has a sketch map of a canal system overlaying real-world Martian geography, character templates for half-a-dozen subspecies of humanoid Martians, and brief write-ups of three different Martian cultures (mercantile Mariner Valley, the Acidalian Theocracy spread across the dry seabed of the Boreal Ocean, and an insular kingdom in the Hellas basin.