How do I add a game to Steam I've purchased somewhere else? [duplicate]

Possible Duplicate:
Can I register a retail boxed copy of a game with Steam?

With the addition of Greenlight to Steam a decent amount of games that were normally purchased elsewhere can now be purchased through Steam. I noticed Project Zomboid was among the titles to be added to Steam. I have already purchased Project Zomboid from Desura, and whenever the game is added to Steam I would like to put it on my Steam account.

Is this possible and how do I do it?

2 Answers

Sadly there's not really a universal way to transfer games purchased elsewhere to Steam. Some games will provide Steam keys when purchased elsewhere, but for the most part you're out of luck.

What you can do is to add a shortcut to the game to your Steam library. This Steam article describes how to add a non-Steam game to your library. This will let your friends know what game you're playing, but you won't have Steam integration.

It is possible to do this.

1. Open up and log into Steam.
2. Look at the menu bar at the top of the window and click on "Games".
3. The last option under "Games" is "Add a Non-Steam Game to My Library".
4. Click on this option.
5. A window will open up, and Steam will scan your hard drive for installed programs.
6. Select the game you want to add.
7. Click on the "Add Selected Programs" button.