For some time now, gamers have known that $10 upgrades are coming for cross-generation console games. Players will be able to buy games on current-gen consoles and switch to next-gen versions later on. Publishers don’t want gamers to have to wait until console launch day to make their Call of Duty: Ghosts or Watch Dogs purchases.

Though individual games (such as Ghosts) have had their plans fleshed-out, the specific details of just how the upgrades will work haven’t been. Sony today ended the confusion and detailed its PlayStation3/PlayStation4 upgrade plans.

Gamers will be able to buy four different games for PlayStation 3 and upgrade them to PlayStation 4: Call of Duty: Ghosts, Battlefield 4, Assassin’s Creed IV: Black Flag, and Watch Dogs. The games can be bought in either physical or digital versions. For digital versions, games will come with automatic PlayStation Network ID-associated access to the $10 upgrade deal in the PlayStation Store.

Disc-based versions are a bit more complicated. Retail copies of these games will come with a voucher code that will need to be entered in the PlayStation Store, unlocking the $10 next-gen offer. In addition, the PlayStation 3 disc of the games will need to be put into a PlayStation 4 for players to play the next-gen version – even though the next-gen version is a digital download.

At first glance, the PlayStation 3 disc requirement seems a bit unnecessary. However, it’s quite obvious the obtuse system is in place to prevent resales of previous-generation games. For example, someone planning to play Battlefield 4 on a PlayStation 4 could buy a PlayStation 3 version, take the upgrade code, and sell it back immediately. Even selling the PlayStation 3 version back at half it’s value would mean a $20 discount on the next-gen version of the game.