Io

Io has only recently caught the attention of the Mega Corps and is often the place to go if someone wants to find conflict. No single corporation lays claim to the moon and it seems like it will be that way for a while longer. The official reason why so many people are fighting on Io is for the mineral resources that can be mined. The real reason is that it's the perfect place to hide somewhere on the surface, make a base, and research and/or manufacture powerful, destructive, and more than likely, amoral technologies. 
The moon is also popular with military forces since they can test new weapons, explosives, and tactics without having to worry about the population since the only people on the rock are other soldiers or those in research outposts.

Geography

Mostly mountainous with craters here there made from meteorites or military-grade explosions.
There are pockets of biomes artificially made with breathable air but nothing permanent.

Type

Planetoid / Moon