I had an idea not exactly sure how to implement it. But basically your a superhero maybe speedster maybe something else. But how you play the game determines the final boss.
If you play as a noble hero your going to face a dastardly villain version of yourself
Dastardly Villain you face the noble hero version of yourself. Possibly with various degrees such as ruthlessly pragmatic hero meets idealistic Dr. Horriblesque Villain. Been watching Flash and the idea came thought I’d get some input