Using the Steam Deck as a Controller for my Gaming PC

The Goal and Brief Overview 

I've seen that a couple of people online want to use the Steam Deck as a controller for their pc, kind of in the way that the Wii U gamepad controlled the Wii U console. Valve does suggest how to do this here, but without much detail.

The best way I found to do this was actually not through the Steam Deck's native streaming system, but instead by downloading Steam Link through the Discover app. Doing this instead gives us some extra settings. Using the built-in streaming, you get full remote play, showing the computer screen on the Deck, playing audio out of the Deck, etc. Perfect for if you're out of the house, however, when I'm still sitting at my desk in front of my PC, I don't really need my game controller playing noises or showing my monitor screen, and Steam Link lets you disable that. Also, using Steam Link rather than the built-in streaming system would allow you to close and relaunch any game without stopping streaming, choosing a new game and restarting the stream. You can stay connected the entire time.

Setup

By downloading and using the Steam Link app (you can get it from the Steam Deck's Discover app in desktop mode), you can disable both video and audio in Steam Link settings, which will effectively turn your Deck into a controller. But it can get a bit better too. If you go to the next page of the Steam Link settings, you can choose the "launch mode," effectively choosing what your PC does when the Steam Deck connects as a controller. It defaults to launching Big Picture Mode, which given that I am sitting directly in front of my PC with a keyboard and mouse, feels overkill, so I chose desktop, which will leave my PC on the desktop screen it already was on when the Deck connects.

Unfortunately, this is still a bit finicky. To use any non-Steam games with the Deck as a controller requires launching said game or its launcher through Steam. For instance, I own Watchdogs 2 on Ubisoft Connect. To play it with the Steam Deck as a controller, I had to add Ubisoft Connect to Steam and open it that way. That allowed the controller to work with Watchdogs. You can almost certainly add any other launcher you'd need (Epic Games, Origin, EA Desktop, etc.). For any UWP or Xbox Game Pass games, you'll need to use a tool like Glossi to add them to Steam, but that's not too difficult.

Final Points

It is possible to use the Steam Deck as a controller on PC. Doing it the way I suggest will let you play any game, with the controller on speakers on the Deck disabled, so it acts just like a controller. Steam on your PC will detect the Deck as a Steam Deck, not as a generic gamepad, so you will have full configuration support. 

However, it just doesn't feel worth it to do so. If you own a gamepad already, use that. It'll be easier to set up, doesn't require adding any extra apps to Steam or downloading any other utilities. Otherwise, you could use your Steam Deck for real remote play, through the Deck's built in game streaming, or use something like Parsec or Moonlight, which I personally prefer (Parsec requires a tiny bit of extra configuration to get hardware decoding working, something you'll most definitely want to do, but it's not too bad. Took me like 5-10 min total for installing and setup. Tutorial here). 

You could also just... play the game you want on the Steam Deck. You can get almost any game you could possibly want to work just by doing some configuration in SteamOS desktop mode. For Game Pass games and other games you just can't get working on Linux, dual-boot Windows.