Nvidia is planning to add a new feature to GeForce Experience that will deliver game codes through the client, and the company is currently asking all GeForce GTX Titan X owners to help them test out the distribution system. In return, Titan X owners will get themselves a free copy of The Witcher 3: Wild Hunt.
To help test out the new GeForce Experience feature you'll need a GTX Titan X with the latest version of the app installed. Then, click on the rewards icon within GeForce Experience, and you'll be presented with an option to get a free copy of The Witcher 3. Follow the prompts, copy the code that's provided into Nvidia's usual redemption portal, and you'll eventually be able to download the game.
This game key distribution system appears to be a way for Nvidia to easily distribute their free game bundles. Currently Nvidia relies on paper cards with printed codes to do this, and not all retailers provide the cards with eligible graphics card purchases, leaving some buyers disappointed when they don't get a free game despite buying an eligible GPU.
By shifting the distribution to within GeForce Experience, Nvidia could deliver codes to everyone who is eligible in a much more streamlined fashion. You would no longer have to manually type in a game code, and no one would be excluded from getting a free game.
Fingers crossed this new feature comes out of beta in time for Nvidia's next game bundle later this year.