The first Injustice game—and the excellent prequel comic series that accompanied it—explored a reality in which a grief-stricken Superman cast aside his moral code to rule the world as he saw fit. It seems like the sequel will delve into that story again, but this time a defeated Superman will try to raise himself…
Source: io9 – Superman’s Totally Ready to Be an Evil Dictator Again in the New Injustice 2 Story Trailer