Playtime Booster
The Steam Playtime Booster feature allows you to idle one or more games manually to boost their total playtime.
You can idle a maximum of 32 games simultaneously. This limit is imposed by the Steam client
Click in the sidebar
Click below the game to begin idling the it
Click in the sidebar to view the games you are currently idling
Example
Additional Information
When you idle games with Playtime Booster, SGI creates a SteamUtility.exe (idle) window for each game to make Steam think you are playing those games. This window will close automatically when you stop idling the game, or when you exit SGI.