It was not obvious to me whether the Steam Deck is a separate game system or not, as it is basically a handheld PC running a Linux variant.
Reasons for the Steam Deck being its own system:
even though Steam OS is based on Arch Linux, it is still a separate OS. A similar situation is the Xbox One that runs a modified version of Windows.
Like a console, the Steam Deck has well-defined hardware specifications and controls. All the Steam Deck games already run on other platforms, but you could say the same for Google Stadia or Apple's tvOS, which I already decided to add as systems.
I felt that playing the Steam games on the Steam Deck shouldn't be listed as playing them on Windows, which is just incorrect, and adding them as Linux games also seems wrong, if only because the games are running on a handheld system, which is very much not the traditional Linux gaming experience.
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