I've been into gaming for more than 20 years, since my parents bought me a good ol' rubber-keyed Sinclair ZX Spectrum. The Hobbit, that old text-based adventure, got me into gaming. Since then, I've spent countless hours playing hundreds of games of all colors and shapes. And I can't recall any other game that entertained me the way The Witcher just did.
Some way across the middle of the game, I dropped my mouse, rested my chin on my hand, and spent a good couple of minutes worrying about the moral consequences of the choice that was in order. I didn't care about the rewards, the risk, or anything else. Usually, when you play a so-called "role-playing game" all you care about is your character's ability or stats progression, loot, and risk assessment. When you play The Witcher, you care about who your character is, who he will become, and what will happen to the characters he befriends along the way. Everything else becomes secondary.
The witcher you begin the game with will have little to do with the witcher you end with. As in a novel, the main characters evolve reacting to that ever-changing world that surrounds them and which, in turn, reflects their actions, climaxing in an astounding monument to time paradoxes and feedback craziness. The sober maturity of themes and characters, the astonishing turn-of-the-screw in so many of the excellent subplots, will make you gape in amazement more than once.
I think all that deserves a very special mention.