On returning to the game now, it's the stories within stories that impress most. Those narrative mini-arcs that show the game's tagline to be more than idle boast: "There is no good, no evil - Only decisions and consequences." There's the expected branching storyline, but with very little of the blatant good vs. evil choices that are so clearly signposted in other RPGs. As long as you choose the path that is best suited to how you're playing Geralt, rather than that which you estimate will net you the most loot, you're never made to feel that you've made 'wrong' choice.
Consequences play out as mini cut-scenes in the style of hand-painted storyboards, with Geralt providing a voiceover explaining that the events of right now are transpiring because of the decision that you made, in some cases, several hours previously (there's no quick-loading in order to pick the other choice).
The decision that stuck with me most came on my first playthrough. Having journeyed to an out-of-the-way swamp and completed several of the local quests, I had to choose one side in a conflict: the rebel force or the authoritarian soldiers. Neither side is explicitly good or evil, and you can see the point of view of both.
The rebels are made up of the non-human races (elves, dwarves and the like) and are victims of racism. They've been forced from their homes to live on the edge of poverty. With barely enough food and water for their families, they have taken to obtaining these things by force, which in some cases has led to innocent humans being caught up in the fighting between them and the authorities. You can see the persecution and, in most cases, it would be simple enough to side with them to fight against the 'evil' empire that imposes such oppression.
Except that here the empire isn't evil, and nor is it even your enemy. From the soldier's point of view, the rebels are effectively terrorists and it's not them forcing the suppression on non-humans, but society as a whole. Though the authorities are doing nothing to redress the balance, their interest is in keeping the peace and stopping any further attacks by the rebels.
So do you lead the imperial unit to the rebel camp to rout them completely, or do you lead the rebels in a pre-emptive ambush on the imperial guards camped in the forest? I felt that as a Witcher I should remain impartial and not get involved in the politics, so I continued to go about my business, determined not to help either, although it seemed that neither would attack the other until I acted and both would be stuck in their respective camps for game-time eternity. Eventually I left the swamplands, willing to leave that particular branch of the story unresolved, such was my feeling for remaining true to the neutrality of the Witcher ethos.
But it did resolve. Despite what seems like a two-choice scenario, CD Projekt RED built in an invisible third choice: do nothing, as I had. This choice comes with its own outcomes and pretty storyboards further down the line, and you're chided for your neutrality; reminded that it has its own consequences. Had I created my own character, I likely would have chosen one side over the other, but with The Witcher I felt it was my duty not to choose, because that was what a Witcher would do.
The Witcher's legacy to me is that it encouraged me to play an actual role, rather than flesh out a cipher with a range of canned goods and evils. It illustrated that game developers needn't rely on reward or punishment to make us care about the choices we make: provide compelling narrative, not shiny trinkets, as the preeminent consequence of our decisions and that will be enough. We'll even forgive you the sex cards.