Steam Community :: Guide :: Adding a Non-Steam Game to Your Library

I will give you instructions on how to add an application or game to your Steam library that was not purchased or activated through Steam.

Steam Community :: Guide :: Opting In and Out of Steam Client and Product Betas

Does anyone know how to add a guide for non-Steam games? More info in the comments. : r/SteamDeck

How to Add a Non-Steam Game on the Steam Deck - Pi My Life Up

Steam Deck Quickie: Setting All Five Custom Artworks for A Non-Steam Application/Game

Steam Support :: Find Downloadable Content (DLC) for My Games

Communauté Steam :: Guide :: Steam Summer Getaway Trading Cards

Steam Community (Steamworks Documentation)

Steam Community :: Guide :: Adding a Non-Steam Game to Your Library

How to See Hidden Games on Steam