Sony has provided detailed instructions on how to upgrade select PS3 titles to their PS4 equivalents.
The upgrade offer applies to both disc-based and digital versions of the games in question. Players with the disc version will need to put the PS3 disc in the PS4 console in order to play the next-gen version of the game. The full instructions are as follows:
Disc-Based Step by Step Overview:
Step 1: Disc Only:
Step 1: Open an account on the PlayStation Network (or log in to PlayStation Network using your existing PlayStation Network ID account).
Step 2: Select the PlayStation Store icon on the PS3 system home screen.
Step 3: On PlayStation Store, select 'Redeem Codes' at the bottom of the menu.
Step 4: Enter the voucher code ("Code") exactly as it appears on the voucher.
Step 5: Once the Code has been entered correctly, select 'Continue' on the dialog box.
Step 6: Select 'Confirm' to accept the Terms of Service.
Step 7: Select 'Continue' to complete Code redemption.
Step 8: The Code redemption is now complete. The Code cannot be used again or associated with a different SEN account. Once you have your PS4 system, you can proceed with the next step.
Step 2: TO DOWNLOAD PS4 VERSION OF GAME:
Step 1: On your PS4 system, register the PS4 system with the SEN account through which you redeemed the Code.
Step 2: Select the PlayStation Store icon on the PS4 system home screen.
Step 3: Search for the name of the game on PlayStation Store and select 'Purchase' to download digital version of the same game to your PS4 system hard drive. The discounted price will be deducted from your network wallet according to the Terms of Service and User Agreement.
Step 4: Insert the PS3 game disc into your PS4 system.
(PS3 game disc required to play digital version of the game on your PS4 system)
Digital-Based Step by Step Overview:
Step 1: Buy or pre-order the PS3 digital version of the game from PlayStation Store or Sony Entertainment Network Store.
Step 2: In PlayStation Store or Sony Entertainment Network Store, find the PS4 digital version of the game as soon as it becomes available. The special price will be available for accounts who purchased the PS3 Digital version of the game from the PlayStation Store.
Step 3: Buy or pre-order the PS4 digital version of the game at the special offer price. See Promotion Restrictions for Each Game.