From the Steam Store page:
As humanity endeavored to better themselves, they created the biological marvel known as Gears. Originally intended as the next step of human evolution, they were instead fitted for war and turned against their own creators. A century later, you are left in the wake of the hundred year human-Gear war that nearly destroyed the Earth. Welcome to Guilty Gear X2 #Reload.

Building upon the gameplay and story of Guilty Gear X, #Reload features refined fighting mechanics, new characters and stages, and the same high-velocity multiplayer versus action that put Guilty Gear on the map.