By-mail video game rental service GameFly will be launching an online client that allows for "Unlimited PC Play" later this year. More specifically, members will be able to download and play computer titles on their PC (and later Mac) from an ever-expanding list as long as they remain active GameFly subscribers.

This new service doesn't require a separate subscription, but rather is bundled alongside a standard GameFly by-mail subscription. GameFly co-founder Sean Spector told Joystiq that they have no plans to offer a digital-only subscription, as they believe the real value of their service to gamers is the combination of both console and digital PC game offerings.

"We're talking to all publishers about participating. Several have been signed, but we're not announcing at this time," GamFly co-founder Sean Spector told Joystiq. "In the 'Unlimited PC Play' portion for GameFly subscribers, we expect to have over a hundred titles available for the beta launch, but we'll be adding to the list constantly and should have hundreds at the time of our holiday launch."

GameFly acquired digital game retailer Direct2Drive from IGN earlier this year but at the time no word was given regarding how the acquisition would be used. It's highly likely that GameFly is harnessing this technology to offer the Unlimited PC Play addition.

GameFly will be joining an already impressive list of streaming game sites including Steam and OnLive. OnLive is a cloud gaming platform that launched last year with the ability to rent and buy digital copies of popular titles. A key aspect of OnLive is the fact that games are stored and run on remote servers, meaning you don't need a powerful computer or graphics card to enjoy them.

The service is expected to arrive in time for the holiday season with a closed beta to begin on September 8. You can request a beta invite by visiting GameFly's website and submitting your e-mail address.