If you have a Steam Deck, then, like me, you've probably started to delve into the rest of your Steam library since you picked it up. There are a ton of great games on Steam that play well on the Steam Deck, but sometimes, you'll want to play them on your PC, too. Thankfully, if you don't have a controller for your PC but still want the controller experience on your PC, you can use the Steam Deck as one, and it's pretty easy.

How I used Steam Remote Play to turn my Steam Deck into a controller

It's technically a workaround, but it's Valve-endorsed

If you want to use your Steam Deck as a controller, Valve actually specifically mentions this use case as being possible in the Steam Deck's FAQ. You can do it through Steam Remote Play, which will stream games from a PC on the same network to the screen that you're using, which in this case, is the Steam Deck. However, to optimize the experience, you'll want to change how Remote Play works a little bit.

1. Install the game you want to play on your PC and make sure that if it's a non-Steam game, add it to your library first.
2. Connect the PC and your Steam Deck to the same network. For better performance, your PC can be connected via Ethernet instead of Wi-Fi.
3. On your PC, open Steam, click the Steam icon in the top left and select Settings.
4. Navigate to the Remote Play tab. Make sure Remote Play is enabled.
5. Enable Advanced Host Options, and then enable Play audio on host. Otherwise, the audio will play on your Steam Deck instead.
6. On your Deck, find the game you want to stream in your library and select Stream. If Play is what you see instead of Stream, click the arrow next to Play and select Stream from your PC.
7. Select your desktop PC's name from the pop-up menu. The game will now start on your PC and begin streaming to your Steam Deck.

If you would like to try and reduce latency, if there is some, you can do this easily from your Steam Deck. Go to Settings, Remote Play, and enable Advanced Streaming Options. From there, you can decrease the resolution and enable low-latency mode. This will reduce the visual quality of the game on your Steam Deck, but given that you're just playing games on your PC and you're not looking at your Steam Deck, that doesn't matter. You also don't need a fast internet connection, as it runs on the same network.

I've already used this to play Brotato and Cyberpunk: 2077 on my PC, and I'm looking forward to playing more games with it! It's obviously not as good as just using a dedicated gaming controller on my PC, but it works surprisingly well. While there have been projects in the past like GlosSi that have enabled emulating an Xbox 360 controller on your PC and connecting your Steam Deck to it, the projects that were easy to use have pretty much died since then.

Instead, if you would like a "true" controller experience, you can set up a VirtualHere USB server that will simulate a controller via the Steam Deck. It's a very involved process that will take a bit of setup, but it will work as if it were a native Steam Controller on your PC.