If you have games from Macgamestore.com that you have purchased and are already installed to your Applications folder, you can quickly add them to the Mac Game Store App instead of having to re-download them from the cloud.
In this example we will add the game DOOM 3, which we purchased in 2011 before the Mac Game Store App was released.
1) Launch the Mac Game Store App and go to My Games / All Games.
2) Find the game in the list (in our example, DOOM 3)
3) Click on the down arrow next to that game and select: Find on My Mac
4) Find the game in your Applications folder, which, in this example, is DOOM 3. Double click on it.
DOOM 3 is now linked to your local copy on your hard drive.
You can remove the link at anytime using the same down arrow.