(Not necessarily released this year, just stuff that I've listened to a lot in the past 12 months)
Chvrches, Every Open Eye. Although I listened to both their albums a lot this year, and I think that The Bones of What You Believe is my favourite overall, it was this one that I hadn't listened to before. It's slightly more upbeat than TBoWYB and there's a bit less of the really fuzzy old-school synthesizer tones that I loved, but the tunes are still top-notch.
Clutch, Psychic Warfare. Listening to an album while getting your first tattoo is as good a way to discover a band as any, so thanks, Barney, not only for doing a fine job on my wrists, but also for introducing me to a cracking band.
Bolt Thrower, Those Once Loyal. Like many veteran gamers, I knew of Bolt Thrower from Realm of Chaos, but I hadn't really listened to much of their other stuff before this year, which is a shame because although RoC isn't bad, the three albums that followed it are better, and this, their final release, is better still.
Skeletonwitch, Beyond the Permafrost. Although I'd heard of Skeletonwitch before, it was seeing this record here that piqued my curiosity enough that I got around to checking them out. And I'm glad I did, because they're fantastic, gloriously over-the-top fun.
Savage Messiah, Hands of Fate. I discovered SM last year when I saw them supporting Testament, and saw them again this year supporting Cradle of Filth (although this time it was really SM that I was there to see). Their latest album is a bit of a shift in style; there's much less thrash influence and much more traditional heavy metal. But they're still awesome.