Please note that THQ has released the playable demo on the Marketplace of Warhammer 40,000: Space Marines, the new third-person shooter set in the universe Games Workshop's futuristic-fantasy. The demo will offer a taste of the gameplay of the title, so as to allow you to decide whether to buy it when it arrives in stores Sept. 9. The download will occupy 1.5 GB on your media ( web link ) and, as always, for the first week is only accessible by members of Live Gold.