Steam Box era SteamOS. About a decade ago.

Back in 2013 or so, Microsoft launched the Windows Store alongside Windows 8, and was making some noises that sounded a lot like shutting out independent software stores like Steam and requiring everything on Windows to be sold through the Windows Store.

Valve reacted to this by saying "Welp I guess it's time to start investing in gaming on Linux" and launched Steam Machines, little PCs designed to be connected to a television to bring the Steam experience to the living room couch. They ran a modified version of Debian Linux along with their own tweaked version of Wine that could run some Windows games alongside several (including Valve's own library) that shipped Linux native versions.

The project itself was a bit of a flop; they relied on other companies to make Steam Machines, like Alienware and such. But a lot of things came from it.

1. Valve demonstrated they had the wherewithal to take the gaming market with them if Microsoft got too greedy.
2. Big Picture Mode, Steam Link, and the beginnings of Proton among others came from the Steam Machine project.
3. The Steam Controller came from this project, which I've heard GabeN talk about as a major learning experience they drew on during the design of the Steam Deck, aka why the Steam Deck has perfectly conventional controls.

They spent most of the 20teens adding steady improvements for Linux gaming to the point that we switched from having a list of games that ran on Linux, to a list of games that don't run on Linux because that became easier to manage. Then they launched the Steam Deck, an unqualified successful Linux gaming platform. Then I came here, and then it was now, and then I don't know what happened.