So Steam Deck Can't Run Every Game On Steam?

Here's a news flash. The Nintendo Switch can not play every game.

Valve's upcoming  Steam Deck will not support everything game. While the Steam Deck's hardware is powerful enough to run any game on Steam, the console's Arch base SteamOS system will never allow every game to function on the device. The Steam Deck will use Proton, a compatibility layer designed by CodeWeavers which allows SteamOS to run some Windows-based games.  For those who don't know, the Proton compatibility layer translates DirectX games to Vulkan on GNU+Linux.

At least 2,000 GNU games will work without Proton. Games like "ARK: Survival Evolved", "Left 4 Dead 2", "Black Mesa", "Streets of Rage 4", "Shadow of the Tomb Raider: Definitive Edition", "Metro Exodus", "STAR WARS Knights of the Old Republic  II - The Sith Lords" and "Shadow run Trilogy".  Only 2 of those games appear on Nintendo Switch.  

The Proton, compatibility software  allows the portable console's SteamOS to run Windows-based games like "Sekiro: Shadows Die Twice - GOTY Edition", "Aliens: Fire team Elite", "Red Dead Redemption 2"  and "Killing Floor 2".  None of those games appear on Nintendo switch. At least 8,000 Windows based Steam games are known to be compatible with Proton, and updates make other games compatible all the time.

With so much effort being put into Proton, even more games will work in the future. I think the Steam Deck could incentivize developers to ensure that their games entirely support GNU+Linux natively or play nicely with Proton. Some windows base steam games will never-ever work on Steam decks Arch based Steamos. Games like "PUBG", "Apex Legends", "Destiny 2", and "Fortnite" or just not playable on GNU+Linux. And for many people that's ok. 

Note: SteamOS  contains proprietary software, including the Steam client it self and many proprietary drivers. Steam uses the evil Digital Restrictions Management (DRM) to impose restrictions on the software it distributes via the Steam store.