

If for some reason Steam Overlay does not appear, follow these steps to check if it is enabled. Click "add selected programs" to add them into your Steam Game Library.If it's not shown on the list, click "browse" and search for it. Then click the last option "Add a Non-Steam Game to My Library".Click the "Games" tab on the top-left side of your Steam Client.

This method is assuming you're not using the "Big Picture Mode". To use Steam Overlay in a Non-Steam game, you must add that game into your Games Library and launch it there. This should include games such as Minecraft and Overwatch, to throw a few popular names out there. While Steam Overlay is not guaranteed to work for all Non-Steam Games, most games should work.
