Microsoft has introduced a free cross platform multiplayer gaming service called Games for Windows - Live, allowing Windows gamers to play against XBOX players and vice versa. With Games for Windows – LIVE, you get an online identity – called a gamertag – and a friends list that works across multiple games and platforms including Windows XP/Vista, XBOX 360, and Zune.

You can play multiplayer games with your friends, or play against new opponents online using the TrueSkill matchmaking system with other Windows players or with or against XBOX 360 players (in supported games).

Games for Windows – LIVE lets you add achievements and gamerscore earned in Windows games to your XBOX LIVE account. You can also chat and message your friends on LIVE, regardless of the platform via text and voice chat and earn achievements and Gamerscore that lets you track and compare your accomplishments.

Games for Windows games are tested to support wide-screen monitors, 64-bit operating systems, parental controls, and, in appropriate games, the Xbox 360 Controller for Windows. Soon, you will be able to download additional content for your favorite games, from game trailers to playable demos to new maps and levels.

You can experience cross-platform gameplay with the following games: Universe at War, Lost Planet: Colonies, Gears of War, Shadowrun and more.