Although GeForce NOW is not officially supported or Steam Deck, you can still play remarkably well using the browser on Steam Deck, with a little bit of effort.
First off you will need to switch over to desktop mode and open the discover store.
we recommend you use chrome to play GeForce NOW on the Steam Deck.
Search and install Chrome from the discover app but don't open it yet.
Head to the Start menu and open Konsole under System.
in Konsole, paste the following and hit enter
flatpak --user override --filesystem=/run/udev:ro com.google.Chrome
This will allow the Steam Deck controller layouts to interact with the browser, and also ensure that the C in Chrome is upper-case
Now head over to your Steam Library and hit add a game, then add a non-steam game.
Select Google Chrome and press add selected programs.
Next, head to properties for the shortcut that you just added as you need to add some command line arguments to correct the aspect ratio and full-screen modes.
There 2 options here, one is to allow the browser as usual, which will give you full browser functionality as normal. The second is to set kiosk mode which will make the browser act like an app for a single website.
Pick which mode you want to run (we recommend kiosk mode) and paste the commands before the @@u @@ portion
--window-size=1024,640 --force-device-scale-factor=1.25 --device-scale-factor=1.25
--window-size=1024,640 --force-device-scale-factor=1.25 --device-scale-factor=1.25 --kiosk "https://play.geforcenow.com"
Rename the shortcut to GeForceNOW.
As far as the artwork is concerned you can sort them out in desktop mode by right-clicking the top section here to set a custom background and then in the library view you can find the tile and right-click these and say set custom artwork but this is quite fiddly and if you have decky loader installed this is much simpler and if you don't have decky loader installed then check out our ultimate decky guide.
You will need a GeForceNOW account to play on Steam Deck and you use it completely for free for 1 hour game sessions, you can find all the info and prices for the higher tiers here