For me personally, Grim Dawn. At nearly 400 hours played, it's my third-most-played game on Steam, and for a good reason. I don't love the setting (especially compared to Titan Quest, which... I guess you could call a very close relative), but other than that, what the game does, it does really well.
I don't generally like to badmouth games in these votes, but Doom will have to be an exception. On the surface, it has a lot of what the old Doom games had. In practice, I don't think it feels anything like the old games, and I don't like what it does. I especially don't like the glory kills, which really try to be cool but are annoying as a game mechanic and annoying to watch over and over again. I haven't played Brutal Doom, but judging by what I've seen, the 2016 Doom is a descendant of Brutal Doom instead of the vanilla Doom games from the 90s. Anyway, enough of that, just venting (some of) my frustration with the game - really disappointed with what was done with the franchise, and probably wouldn't mind the game if it was called something else.
For impact, Pokemon Go would have to get my vote, but Grim Dawn is so much better that I can't really vote for Pokemon Go this year. In case it was still somehow unclear, Grim Dawn gets my vote.