Hello Linux Geeksters. Valve has recently changed the description of SteamOS in their FAQ, from “Debian based” to “a Debian fork”. While the initial SteamOS version, called Alchemist was built on Debian 7.1 Wheezy, the Steam developers have implemented a lot of new things to their operating system.
And yes, there is big difference between Debian based and Debian fork, despite the fact that both Debian based systems and Debian forks use the same repositories as Debian. While Debian based systems implement the major changes of Debian, (for example, Ubuntu will replace their own Upstart with systemd, to keep the Debian compatibility), the Debian forks don’t have to stay on the same path as Debian.
And SteamOS is quite different from Debian Wheezy. It has different hardware requirements and support the newest GPUs, runs on a different kernel, uses a different default event manager and a different graphics compositor, etc.