inFamous and Prototype. In both, you play as superpowered individual set loose in the city, where you can wreck havoc on the populace with your new abilities while fighting other superpowered...things.
God of War and Devil May Cry series. Beat-em-ups where you take on an assortment of supernatural monsters, including a few gods along the way. Polished gameplay, slick combat, and completely over-the-top violence.
Deus Ex: Human Revolution and Dishonored. Dark and dreary first-person games with some nice open-ended mission structure and multiple ways to mess fools up. One's cyberpunk and the other's steampunk. And while we're at it, the original Deus Ex and Thief games.