Wrecker II, The Wreckening

Four hundred years in the future, humanity has colonized the exoplanet named SACH-041840 which orbits Proxima Centauri. The colony struggled at first, but over the course of 50 years became self-sufficient and profitable. But in the 55th year after colonization, "they" came; Alien creatures that emerged from the ground and attacked the colony. No one knows who or what controls them (if anything), but what is known is that if they reach the colony proper, it will be annihilated. It is now the 149th year after colonization. Outside the colony, dozens of battle turrets create a perimeter that defends the colony. You are a member of the specially trained fighters operating independently, alone, one per turret. You and your fellow turret operators are the lone defenders of the colony.