It's been a long time coming but OnLive is finally ready to try and silence its critics as the on-demand gaming service makes its official debut today. To celebrate the launch, the company announced a partnership with AT&T to offer U.S. customers a free first-year membership, with an optional second year at $4.95/mo. – down from the regular price of $14.95. Those interested can sign up to the Founding Member Program until July 15; they'll pick people on a first-come first-serve basis.

This won't get you complete and total access to their whole library, though, but rather access to the community, free demos and other content. Full games will cost from $9.99 to $49.99, depending on the title, while for those who don't want to pay for something they don't 'really' own, three or five-day rentals for five dollars will be available as well.

If you haven't been following the news, the idea behind OnLive is that instead of running a video game locally, players connect via broadband to a gaming system that runs and stores their data and the entire game itself. The service hopes to mark a big shift in the way gaming works. Not only it promises a fluid and lag-free experience on Windows and Mac OS X systems with very low hardware requirements, it also gets rids of downloads, patches and physical discs.

The service is launching today with over 20 titles available, including Prince of Persia, Tom Clancy's Splinter Cell, and Mass Effect 2. A "MicroConsole" that can be attached directly to HDTVs will be arriving later this year.