Mars is much as it was imagined by Science Fiction writers early in the twentieth century. Small, bitterly salt seas are all that was left of oceans much like our earth’s. Canals bring the water across the land, nurturing scanty crops in the semi-arid lowlands. Across the highlands, nothing much grows - sparse hardy weeds nurture small herds of grazers, which in turn sustain a smattering of carnivores.
Mars was once as wet and warm as earth, but as the sun dwindled, the planet aged and shriveled up. Ancient and majestic ruins dot the higlands, where once fertile land has dried up and blown away.
The lowlands of Mars were at one time the ancient ocean beds. The
highlands were at one time the islands and continents, and between the
two there is a scarp, which was once the continental shelf. All of the
lowland cities are relatively new as Martian cities go. The famous
canals were dug over time, as the shrunken seas gradually retreated away
from the continental shelves. Now, some of the lowland cities are very
far indeed from the life-giving water.
The Martians and Mars Humans who live here try not to think about the future, but one day, Mars will be as dead as Titan. In the meantime, the slow decline of the once powerful Martian Houses goes on apace. Once capable of cracking a planet into luimps of rock, the Martian Houses bend over backwards to curry favor with the now dominant Earth nations.
Mars is cold and the air is thin, like alpine regions of the earth. Humans have trouble in the highlands, though this is mitigated by Mars’ light gravity. The lowlands are somewhat better, and thus where most earth tourists stay. The great Martian cities of the lowlands still thrive, and the tourist exchange is welcome.
The Martians have forgotten much of the technology that brought them into space long ago. Their colony on Mercury was out of touch with the homeworld for centuries because they were forgotten about after a war, when the coalition that sent the colony out was defeated and records destroyed. Earth-sponsored archeological expeditions into the ruined cities of the highlands occasionally yield a rich trove of forgotten technology.