Of course a game can't live up to a novel in terms of storytelling. That is impossible by the very nature of the mediums.
Games have their own strengths. But one shouldn't be surprised that an author of novels doesn't want a game to continue their stories...
I hope I wasn't giving the impression that I disagree with Sapkowski. On the contrary, I agree with him wholeheartedly. I like the gaming medium due to its ability to allow interaction and immersion in a world, just as film is a good medium for observing physical expression and feeling, but nothing trumps a book on plot, character development, general description and depth. In games we have combat, inventory management, quests, and other filler that, while it offers immersion and interaction, it, by its very nature, minimizes depth for the sake of fun. There's nothing wrong with that per se, but I think someone would have a really hard time arguing that a game can surpass the book it was based on in terms of depth, intricacy, character development, plot, or any other narrative device for that matter.
Sometimes when you are reading a book, you have this tangential imagining of being in the world you are reading about, wishing you could alter or shape events that trouble you or even just to be able to participate in them. I think this is where the gaming medium shines, it allows someone to scratch that itch.