Man, this game is fun.
A few years ago, a game was created for the second Spiderman movie that had you take control of Spidey giving you the choice to follow a linear storyline or just basically swing around the city and stop crime/help citizens. It was a fantastic concept - so easy yet never accomplished correctly.
Suckerpunch and Sony Entertainment took that idea and ran with it by creating an original character and giving you the option to either become a superhero OR a supervillan. I haven't finished the game yet - I doubt I'm even close. Currently, I'm playing through as a hero and am having a total blast but at the same time, I'm excited to be the villan.
Unfortunatley, it's a PS3 exclusive so a whole lot of people are going to miss out on this one. However, if you have a PS3 - pick it up. You won't regret it.