Witcher 3 Blood and Wine was the best gaming experience for me this year. However, since we are talking about new games, for PC at least, it's a split between Rise of the Tomb Raider, The Witness and Dishonored 2 for me.
As much as I want to say Doom, I just haven't played it enough, from what I did play it was fantastic but it hasn't drawn me back in. Apart from older games which I still play, the one game that stands out this year for me is Hitman, I have nearly 100 hours in the game due to the near endless replay-ability of all the maps and I still haven't even played the newest map or played the two before that to their fullest. I easily have another 50 hours of gameplay not including the monthly targets and user created content. The game might not be for everyone but it's well put together, the visuals are top notch, controls work well, easily my favorite game this year. I really hope they continue to expand on it and follow through with their seasons concept, time will tell.
I played through the original Far Cry this year for the first time (I have beat 2 and 3).
It is surprisingly quite decent looking and other then some goofy AI at times I enjoyed it, took me about 14 hours on medium difficulty, played it through on my XPS laptop.