In 1988, GDW published a role playing game called Space: 1889. The brainchild of Frank Chadwick, the game takes place in an alternate universe that more resembles the worlds of Jules Verne and Edgar Rice Burroughs than it does our own.
Thus, Mars is a planet populated by ancient races who built a network of canals in an attempt to save their civilization from the encroaching desert. In the universe of Space: 1889, the Canal Martians live in the remnants of their once proud cities while fighting off their barbarous cousins who live in the steppes and high plateaus of the Red Planet.
The Moon is honeycombed with caverns where the insectile Selenites hide their secrets.
And Venus is a planet-wide swamp full of dinosaurs and primitive amphibious natives.
When Thomas Edison invents a space drive, the Ether Propeller, he opens these strange worlds to the imperial nations of Earth and a wave of interplanetary colonization quickly follows.