The Injustice development team shared a video detailing the "Red Son" content players will be able to get for the upcoming fighting game. There will be alternate costumes for Superman and Wonder Woman based on their looks during the "What if" storyline for Superman. They've also created a new costume for Solomon Grundy to fit the theme as well.
This isn't just a costume pack, either. Players will get an additional 20 missions in the scenario mode based around the Red Son comic.
Below is another video from Injustice that shows off some of the story stuff from Lex Luthor if you're in the need for some more superhero fighting.