In 2013, NetherRealm released the surprise hit Injustice: Gods Among Us, following it up with a sequel four years later. The Injustice series takes place in an alternate version of the DC Universe, where Joker tricks Superman into killing a pregnant Lois Lane while detonating a nuke in Metropolis at the same time.
After these tragic events, Superman goes full-villain, establishing a tyrannical regime on Earth, with Batman and Lex Luthor being the only resistance.
In the sequel, Injustice 2, order has been re-established across the world, Superman has been detained and (unbeknownst to everyone) Supergirl has arrived on Earth. However, when Brainiac arrives to finish off the remaining Kryptonians, Batman is forced to team-up with Superman to save the day.
After defeating the aforementioned Brainiac, players are presented with a choice, deciding whether Batman or Superman is victorious, the conflict between the two inevitably restarting in the finale.
Both endings are radically different (as you'd expect), yet leave the future of the Injustice universe ambiguous, so here are some directions it could take...