I would make it so your game registeres to your account or has a code that comes with the game. Once you put in the code or register the game, that will be the last time you have to. However if the next person doesn't have access to the code, the second hand buyer would have to pay a fee to register the game to their account. This fee would go towards the software company, Say $10-$15.
EDIT: Also what if they add in a buddy system. so you get 10 buddy's you can share your game with, however they have to be your buddy as well. you could change your buddy system once a month. Just random Idea's. This would be if the code could only be used once.
Yes people would just have to keep the code and sell it to gamestop. However you could limit the use of the code. Just the amount of people losing the code would have enough effect to limit the damage done.
I just thought of this, so feel free to pick it apart.
Oh and to prove I don't sell back my games or just to make you really jealous. LOL This is five years of collecting.
