I honestly thought I'd vote for StarCraft II: Legacy of the Void. It was a great game, a fittingly bombastic finale to a series I truly love. While the gameplay was entertaining as ever, it was the visual design, the writing and above all the VO performance that kept me glued to the screen.
And yet, only a month after I finished the game I find it really doesn't occupy my mind at all. As good as it was, I can't say it had a very lasting effect on me, or that it particularly sticks out in my mind.
You know what does?
Bloodborne.
I'd never played a FromSoft game to completion before, and it took me a long time to get through this one, but I stuck it out despite all the frustration, and for that I was rewarded with something special. It satisfied my itch for action, horror and mystery in equal measure, and even though all of my stated preferences for storytelling dictate I should have hated the way in which Bloodborne presented its story and lore, I loved it. The community buzz around it was a welcome bonus, as discussing ambiguous snippets of content was equally interesting as finding them in the first place.
I'm grateful for this game being accessible to folks of middling skill (such as me) despite it being tough as nails. It never felt like a slog, despite occasional frustration, and its challenges rarely felt unfair. It was determination that saw me through it, and I still feel rather good about having been able to beat it.
And the atmosphere... oh Lord, it'll be a long while, I feel, before I'll get to experience something dripping with atmosphere like Bloodborne.
My GOTY 2015, no question.