I've been playing a game on my Deck that's been reported as unplayable (Hitman, the remake) and I can't figure out what's supposed to be wrong with it. The stupid online requirement works, for better or for worse, so it's not DRM. The only thing I can think of is that I can't use the controller to click the Play button on start (need to use the touch screen) but that's rather minor.

I've seen other cases where "not working" means "you need to hit Steam+X manually to open the keyboard in certain settings". These playability standards seem rather high, which isn't a bad thing, but can sew the numbers. On the other hand, you an find plenty of stories of users playing verified games that become bad later in the game, presumably because no company is going to spend 100 hours on every game to verify that every single thing works. I haven't run into that yet, though.

Steam Deck and Proton really changed gaming on Linux and otherwise. Certain features of well-integrated games (Euro Truck Sim providing a list of named actions for key binds, for example) are unlike anything I've seen elsewhere. The ability to add overlay menus, with multiple levels even, to any game add even more to the way you can play PC games with a controller.

At this point, I hope Valve releases a second Steam controller: one that's just the Deck without the PC inside. Coupled with the new Steam Big Picture, I'm confident Steam consoles could take off.