For me? The Order 1886 actually. Great replay value due to cinematic story and I loved the brutal gunplay. Haven't played Witcher 3 yet and I expect Batman and MGS to overtake it but it could very realistically finish top 5 for me this year I love those type of games.

Completely forgot about Ori  

Played it twice and thought it was sublime, not sure how I forgot. 

I believe that I have yet to play a game from 2015.

The Witcher 3, been playing it for almost 3 weeks now and finally starting the ending main quest.

I personally can't remember the last time I had so much fun with a puzzle game. Though I can see that this game is not for everyone. 

If you like puzzle games then you'll love it, but otherwise I think you should pass or wait for a price drop. At the end of the day is the same "connect 3 of the same color" type of gameplay with some twist here and there, and with (surprisingly) a lot of strategy involved, at least compared to other puzzles games.

Witcher 3 for me.

Ori and the Blind Forest.

Even with Batman 3 coming soon, I doubt it is going to be topped.

Bloodborne and witcher 3.

Bloodborne.

Only two hours of play and second place goes to Monster Hunter 4.

Pillars of Eternity and Bloodborne are at the top of my list. Though I think the dark knight is going to leapfrog over both games.