Batman: Arkham City is out today in the US, but Europeans will have to wait until Friday to save Gotham. Wherever you live, you can play a free demo of Batman: Arkham City right now through the cloud gaming service, OnLive .
Once you've signed up for a free account and downloaded the client simply search for Arkham City in the games list and launch the free trial. It's limited to 30 minutes, but that'll give you chance to take control of Catwoman and thrash some burly men with Arkham City's super slick combat system. Hold down the crouch button while moving for some comedy cat-crawling.