And cause I'm a lore guy?
This is an AU. Duh
So... the company from Casualties: unknown decided to use them to fight in wars for people instead of sending them off to a different planet, so that's when this takes place.
Actually, this takes place in the same universe as Casualties: Unknown.
"In Gunsaw, several different species originating from the Experiment are present, as well as basic civilization and warfare.
These new species were sent by the Company, as they remove every Gunsawian from their labs. During the events of Gooey 78-85 years after CU, there are no more Gunsawians on Earth.
Alongside the new species, the Company sent a incredibly large number of firearms onto the Grey Planet to observe what would happen. This naturally led to war, thus forming the setting for Gunsaw.
On the Grey Planet, however, exist 100-200 thousands of Gunsawians." (from the Casualties: Unknown wiki.)