Half-Life developer Valve has announced today that its online delivery platform, Steam, has now exceeded a total of 13 million active accounts. The milestone was reached just two-and-a-half years after the service gained recognition and mass popularity alongside the release of Half-Life 2.

"We've approached the development of Steam the same way we treat our online games; we release something we've tested, we internalise the feedback, and then we release new features and functionality based upon the feedback received," says Gabe Newell, president and co-founder of Valve.

Newell added, "In Steam's case, we have millions of customers who are gamers and dozens of customers who are developers and publishers. In the past year, we've added over 100 new titles from third parties; grown to over 13 million active accounts, and introduced new features such as Guest Passes and Free Weekends. This growth has taught us a lot and inspired many additional features and services that we'll be releasing later this year."

The system was originally conceived as a way to update Valve's software releases, but has since blossomed into a source for a whole variety of games provided by it and partners, as well as trailers, demos and other features.