Visually, nothing this year wowed me more than Ratchet & Clank. The bright colours of the vistas and detail of the models was breathtaking, plus there was the added bonus of seeing levels I'd played back in 2002 on the PS2 recreated in HD.
On the story and atmosphere front, the twin releases of Bloodborne and SOMA last year gave me two of my favourite brands of horrors coupled with some unexpected twists. Someone on the thread mentioned it already but it bears repeating: Bloodborne's shift from relatively mundane horror to Lovecraftian was executed brilliantly, with lots of subtle hints dropped throughout before everything officially goes off the rails at Byrgenwerth. For me, the turning point was when you get sent to Yar'ghul (an entirely optional event, mind you), the first time you have to deal with enemies who appear to have an intelligence behind them. The Amygdala statues around the place hint at what's coming later and the whole time you're listening to this eerie background choir, hinting at the disturbing ritualism behind everything. It's probably the best use of atmospheric music in a game since at least the first Bioshock.
As for SOMA, I just love that there's a horror game set in the deep sea, which is my favourite setting for horror. But of course, as those who have played it know, the horror elements are probably the least interesting part of the game when compared to the story and concepts it plays with. I can't remember the last time I played such a thought-provoking game. That said, there are plenty of viscerally amazing moments as well, like the walks across the ocean, the leadup to exploring the site where you get your deep-sea dive suit and the nerve-wracking "follow the lights" section. Even if a lot of the horror sequences wore out their welcome, I adored that bit.