Here is a video I just made showing how a sea would cover the surface Mars. It is interesting to watch what happens as the sea level changes and the surface features that brings out.
In the latest beta version of Earthsim we have added an experimental Planet Editor. Over the next year this will be changed quite a bit as we add a more physically correct model of planets.
Right now you can change some of the basic rendering settings for the planet data. In future we will let you change physical parameters for a planet and then run the simulation to see what happens.
The goal here is to let you set-up a physically correct planet with an atmosphere to let Earthsim calculate temperatures and rainfall on the surface of the planet. This then will allow a simple biome simulator to grow of kill life on the surface. This also allows for much more realistic surfaces to be generated for a planet as grasses, trees and plants will know where they can grow.
And here are the latest high res screen shots of Mars. Watch full screen or zoom into the pictures they are captured at 2048x1152.