While you can launch games not purchased from Steam in its desktop app, games from the Microsoft Store or PC Game Pass need a little help to work.

How to add Star Citizen to Steam You can add non-Steam games to your library via the 'Add Non-Steam Game' button in the bottom left-hand corner of the Steam app.

You can also add the WoW Classic executable as a non-steam game for ease of access, following the same guide to find its root folder. But this may prevent Battle.net from updating correctly.

Beyond the basics of running your Steam library on the go, the Steam Deck is a beast at emulation and game streaming thanks to EmuDeck.