Transferred from: http://game.ali213.net/thread-5693230-1-1.html
I have perfectly solved the following method:
How to import a retail edition
1: Do not have any GTAV download process on Steam, if please delete.
2: Then enter the Steam\steamapps\common, if not, you can create your own.
3: Copy the game in it. The name of the game folder must be Grand Theft Auto V
4: Go to Steam, click Download. Steam will then find the Gtav game cache and wait for the verification to finish.
5: After the verification is finished, it will go to download the other parts of the game, the first point tentative. Generally it will show all to re-download, at this time do not panic to continue the next step
6: Re-enter the Steam\steamapps\common, the contents of the inside will be deleted do not be afraid that the real body of the game has been moved to other folders by steam, and then continue to download the common in the steam point to delete the files inside you will find the download progress of a catty of 99%, The game ontology has been correctly identified, and when the game is downloaded, you can enter the game.
Pro-Test available!!
Steam Import the downloaded good game