Prior to the coming of the rifts, Mars had been colonised by the CAN, who had begun terraforming procedures. When the rifts erupted across the solar system, a large swathe of Mars was transformed into the Splinterzone, a region of dimensional overlap and bleedthrough where multiple versions of Mars blend together. Descendants of the human and mutant survivors of the CAN colonies now mingle with strange refugees from various iterations of Mars and demonic supernatural horrors.

The dimensional bleedthrough has affected the environment of Mars, transforming it beyond what human terraforming could have accomplished in the same time. The atmosphere is thin and the oxygen content low, somewhat similar to high altitude conditions on Earth. The temperature is also low and the planet is dry and arid, the few large bodies of water being mostly shallow, salty lakes. Despite the hostile conditions, a pandimensional ecosystem has emerged (see Life on Mars).