For some time sharing games, that have been purchased through services like Steam and Origin, has been impossible. With the advent of Steam Family Sharing, however, you can share access to PC games–both purchased and activated on Steam–with friends and family.
In this tutorial, I'll explain how Steam Family Sharing works and I'll show you how to started. I'll also show how you can control and revoke access to your library when you're sharing.
Steam Family Sharing Explained
Steam Family Sharing works by allowing one person, person A, to authorise another person, person B, to access their Steam library on a given device. You can authorise up to ten devices for up to five other people with Steam Family Sharing.
You can only share your entire library not just individual games.
Furthermore, when person A is playing games in their library, it cannot be shared to and accessed by person B. If person B is playing a shared game and person A wants to access their own library, person A can immediately play their selected game while person B will be prompted to quit and given a five minute period to finish up.
If the library contains add-on downloadable conten, or DLC, this will be shared–as long as the receiving person doesn't own the respective base game. If they already own the game they won't get access to any of the DLC for this game.
If your library contains a game that uses Valve Anti-Cheat, or VAC, and a person you're sharing with becomes banned, that ban is also reflected on your profile. Additionally, any region-based restrictions will still be enforced and, at the decision of the developer, some games won't work with the service at all.
If you have additional questions about how the service works, refer to the Frequently Asked Questions about Steam's Family Sharing page.
Authorising Devices for Sharing
Before authorising other accounts to access your own library, you must first authorise any devices on which others will play your games. This will require you to log in to those devices with your Steam account, so it's important to emphasise that you should not share your Steam account password with anyone under any circumstances.
To authorise a device, in the Steam client, open Steam > Preferences in the menu bar (Steam > Settings on Windows) and select the Family tab. Then, click the Authorise This Computer button. You can then log out of that device.
Authorising a device will count towards your maximum limit of ten devices, though you can de-authorise a device at any time to make that slot available again.
Authorising Accounts for Sharing
Once you've authorised a device, you can authorise accounts to access your library on that device. Before you can do this, ensure the person, with whom you want to share, has logged into the Steam client on the chosen device before.
To authorise a new person open Steam > Preferences (Steam > Settings on Windows), select the Family tab and tick the box next to their Steam community name. Click OK to confirm this.
Once this is done, Family Sharing is fully enabled and authorised for the chosen account. All the games in your library will now be visible in your friend or family member's library, with a tag to note that it's being shared by you.
To launch a shared game click the same Play button as per normal, owned games. When the owner of the library launches a game, however, the sharing person will be prompted to save their progress (when appropriate) and quit within five minutes. These prompts will appear on a minute-by-minute basis before automatically quitting.
Managing and Revoking Access
Unlike the process of authorisation, managing and revoking access to your Steam library can be handled entirely within your own Steam client. To do this, open Steam > Preferences (Steam > Settings on Windows), select the Family section again and click Manage Other Computers.
To revoke authorisation for a specific device, and free up one of your ten slots, click the Revoke link next to the name of that device. For reference, the Steam community name of the person who uses that device to access your library will be shown under By Steam User.
Note, however, that if the person is authorised on any additional devices, they will still be able to access your library on those particular devices.
To revoke access to a person (and free up one of your five slots), click the Revoke link next to the name of that user. This listing will show the user's current Steam community name, so you should reference the time they were added if unclear.
In this tutorial, I've shown you how to set up and manage Steam Family Sharing. Though it maintains many restrictions, the service offers one of the first ways to legally share digital games for the PC and Mac.
If you have any additional questions about Family Sharing or Steam on OS X, be sure to let me know in the comments section.