Cheats and Walkthroughs
This is one of those good news/bad news situations. The good news is that Injustice: Gods Among Us has a confirmed DLC pack that was inspired Mark Millar's superb comic book miniseries, Superman: Red Son. The bad news is that the DLC is confirmed by way of a UK-only limited edition offer that packs in the DLC for free with the game.
Of course, DLC tends to not remain restricted to the realm of pre-order bonuses or regional exclusivity when there's money to be made. The content pack includes 20 missions set in the alternate universe spin-off's timeline along with three character skins, for Superman, Wonder Woman, and Solomon Grundy. Too bad there's not one for the Russky Batman as well.
Also, while I've got your attention: read Superman: Red Son. It imagines what would have happened if the spaceship that delivered Kal-El to Earth had crashed in the Soviet Ukraine, and it's great.