The Batman: Arkham Asylum demo is up, and weighs in at a portly 2gb. The third-person action game seems to be earning reactions ranging from the satisfied to the hysterical, but at least you can judge for yourself in this instance. You can get it here or here. The PC version of the superheroic skull-thumping game is out September 15 in North America and September 18 in Europe, and will include PhysX support and GeForce 3D Vision stereoscopic 3D, which seems like a 3D too many. Three hefty game footage trailers sit below, making for more Batman action than you can shake a batarang at, should you happen to have one.