One of the many things that The Hitchhiker's Guide to the Galaxy taught me is that there are multiple dimensions out there... or out here... or... just... in existence. So in some other dimension, super heroes exist. Unfortunately, we got sort of a lame-o dimension and we just get to read about super heroes in our fiction and in our RPGs. Aegis Studios, with their Superstring Multiverse books, let your Mutants & Masterminds characters travel to alternate dimensions in order to fight crime. The second book is now available.
This book introduces two new alternate-dimension worlds. World 1 is an idyllic world that is sort of if Dudley Do-Right was where you were playing your game. At the opposite side of the spectrum is World 5. This is the Christopher Nolan version of things. Grim and gritty. You can just see everything in those 50 shades of grey now, can't you? ... Wait... that'd be a different universe entirely.