Diablo III - Add as a Non-Steam game

This will allow you to run Diablo III with the Steam overlay.

1. In Steam, click Games (at the top), then "Add a Non-Steam Game to My Library".
2. Click "Browse...".
3. Browse to the folder where Diablo III is installed and select the "Diablo III.exe" file.
4. Click "Add Selected Programs".
5. Right click on "Diablo III" in your Steam Game Library and click Properties.
6. In the Target input box, add " -launch" to the end (without quotes and with the space).
7. Click Close.