They could leave the nature of the destruction of Krypton vague, with the only details given to Kal-L being that it was destroyed by an entity known as Vril Dox. Meanwhile, LexCorp, led by charismatic mayoral candidate Lex Luthor, is aiming to create the most advanced AI in human history, dubbed "Brainiac." At the climax, where Brainiac takes on a robotic body and begins an attempt to miniaturize Metropolis (a destructive and chaotic process), it is revealed that Brainiac is Vril Dox. Sure, fans could see it from several miles away, but to the GA, it could be quite a twist if played right.