But what about the preexisting life? The duality of fire and ice would make for a rather violent atmosphere (wind). The constantly changing weather patterns would make things interesting.
I would totally love to see the world with a native bioluminescent fungi ecosystem. These fungi could produce mountains of dark spores that would blot out the sun, leaving the sky a dark roiling twisting never ending storm with the occasional lightning (but no rain since the clouds are spores not water). The spores could be what are so deadly to humans, but they have technology that can eliminate the spores in a small area.
With so much volcanic activity, the main source of energy and nutrients for the fungi would be geothermal hot springs which would litter the area, creating a multitude of oasis amidst the frozen landscape. These fungi and hot springs would also be the source of the rich mineral deposits on the worlds surface (which is why the THMPR is so useful as opposed to deep mine drilling). As the fungi absorb the minerals from these springs they store them in high concentrations and then when they die their remains get burried and turned into a sort of coal, only stuffed full of lucrative resources rather than fossil fuels.
Because so little sunlight makes it through the spore clouds, almost all life in this biome would have some sort of bioluminescent properties, animals would use it for anything from courtship to territorial conflicts to catching food. The mushrooms would trend towards the higher end of the visible spectrum (blue, indigo, violet) and might pulse or shimmer a bit. Animals on the other hand would range all over (and beyond) the visible spectrum depending on their species and activity. Some animals would show up brilliantly if the player turns on their Infrared overview while others might show strange lines and symbols etched into their chitin shells when ultraviolet is selected.
Life on EM-8ER would not use carbon based deoxyribonucleic acid so none of it would be edible for humans (and vice versa). Instead they would be forced to utilize hydroponic systems to provide sufficient food production. The terraforming process would clear the air of spores and remove any major biological dangers to humans but due to extremely rapid plant growth would be unable to completely remove the actual plantlife itself. As one ranges further and further from the centrally located base the native flora and fauna would take over from human seeded life and there would be a biological battle all along the terriforming border. The lack of natural sunlight normally would render most plantlife dead in a matter of days, however the bioluminescense given off by the fungi mirror natural sunlight, allowing the introduced plants to survive.
While the mean planet temperature would average in at around -40 Celsius, The Silicon nature of the native plantlife requires a much higher temperature to remain functional. Combine that with the hotsprings and immediately around each oasis the temperature would be much much hotter, anywhere from 35 to 50 Celsius. At these temperatures water will easily evaporate, so immediately within a fungi biome there would be lots of condensation in the air as well as pools of liquid water. However this can also be an environmental hazard as one of the chemicals used by native plantlife is Hydrogen Sulfide, which occurs in great abundance from the hotsprings. This renders natural bodies of water toxic to humans and can potentially cause explosions where the H2S pools (it is heavier than air).
The Tsihu actually share the same Silicon based design as the native plantlife and are unaffected by the spores, giving them a massive advantage when it comes to living on EM-8ER, however the incredible value of both the mineral and biological resources on the planet spur human corporations to ignore this fact and challenge the enigmatic alien race for control. Because the Tsihu are perfectly capable of surviving in the "mists", they can appear out of the dark spore laden atmosphere to attack a base from any direction at any time, forcing its inhabitants to stay alert and on guard.
EDIT:
Something reminiscent to the beginning of this song would go really well as exploration music:
