The chatter surrounding the multiplayer aspect of Splinter Cell: Conviction began late last month, culminating in yesterday's release of the co-op teaser trailer on Xbox Live. Well, I can one-up the trailer. I've actually played the mode. Everything you may have heard is true: The main co-op mode (either online or local play, with a human partner or A.I.) is a prequel to the events of the game and doesn't star series staple Sam Fisher. Instead, the estimated 5- to 6-hour campaign focuses on two wetworks operatives -- one American, one Russian -- who must work together to recover stolen nuclear warheads before they're sold on the black market. The game will also feature co-op play in what are being called "deniable ops" -- more conventional intrusion missions and the like -- as well as a player-vs-player-vs-CPU "duel" mode. What I played was part of the the prequel campaign: an admittedly brief but eye-opening mission set in Moscow's fortified metro system. You can watch a walkthrough video of the section I played above. Read on after the break for my thoughts.