In alphabetical order:
Agents of Oblivion by Reality Blurs: This horror-espionage mash-up gives you the tools to run almost anything from James Bond to the X-Files to Men in Black. You can even amp it up further, making the PCs mutant super agents. It even meshes easily with Realms of Cthulhu for as much, or as little, crossover as you like.
WHY IT DIDN'T MAKE THE TOP SIX: Timing. If I had reviewed this in a separate year than Realms of Cthulhu, this would almost certainly have made it into the Top Six, but I have a "one book per publisher" limit that I impose on the Top Six, and at the end of the day, I feel Realms just brings more to the table.
Caladon Falls by Savage Mojo: Caladon Falls is a fantasy setting/campaign for Suzerain, taking a grittier and more warlike approach than you typically see from fantasy games. In fact, it is largely Band of Brothers meets Lord of the Rings, and it's a very impressive campaign that takes full advantage of the Savage Worlds strengths, namely the ease in PCs commanding NPCs and the Mass Combat rules.
WHY IT DIDN'T MAKE THE TOP SIX: Timing. Fact is, I had to choose between this and Savage Suzerain and as great as THIS book is, THAT book lays all the framework for the awesome twist on Savage Worlds that is Suzerain.
Hellfrost by Triple Ace Games: One of the coolest (no pun intended) fantasy settings that I was very much "late to the party" for, Hellfrost is a dark fantasy setting for Savage Worlds in a world that is freezing quickly. With some great setting rules and a gorgeous bestiary, Hellfrost won me over nearly as soon as I sprang for my copies.
WHY IT DIDN'T MAKE THE TOP SIX: Notice that I said "Hellfrost", which isn't a single book, but three books: The Hellfrost Player's Guide, The Hellfrost Gazetteer and the Hellfrost Bestiary. Honestly, I came very close to nominating both the Player's Guide (because the bulk of the setting is right there) and the Bestiary (because I love monster books, and this is a very well done monster book), but I ultimately split the difference and went with the Top Six that you saw on January 1st.
Horror Show by Bedrock Games: Bedrock Games impressed me with Terror Network and Crime Network, their anti-terrorism and mafia RPGs, neither being subject matter I'm particularly enthusiastic about. In 2011 they took their skill based system and applied it to cinematic horror, in a combination that probably shouldn't have worked as well as it did. In fact, Horror Show wound up being a very pleasant surprise for me, a well-researched horror RPG with a tested system and a lot of love behind it.
WHY IT DIDN'T MAKE THE TOP SIX: The biggest reason is that it is essentially a horror toolkit, and there are horror toolkits out there. It came THISCLOSE to making the Top Six, but I ultimately decided that Ghostories had the more unique hook that would sway someone into trying it even if they already had a go-to horror game, whereas Horror Show seems less likely to sway someone who is already pleased with their horror options.
Part-Time Gods by Third Eye Games: The third corebook by Third Eye Games covers all new territory for the small, but impressive, company: Playing Gods. Sure, this isn't unheard of in RPGs, at all. Where this one is unique from those is that the Gods are still bound to their mortal lives, and have to strike a balance between being Gods and being humans. Utilizing a simplified version of the Dynamic Gaming System to bring the over the top powers of the Gods to life, Part-Time Gods is a worthy addition to the Apocalypse Prevention Inc. and Wu Xing line-ups.
WHY IT DIDN'T MAKE THE TOP SIX: Part-Time Gods was a HUGE success on Kickstarter, which led to a few top tier donors making it into the back of the book as characters. The "vanity buy-ins" just kind of annoy me. I'd prefer the page count being used for things I'll actually use...but I did only pay cover for the book, while they shelled out more. The other thing was that, for maybe the first time, I read an RPG that has multiple PC "factions" (Theologies in this game) and not one of them really GRABBED me. I can usually find a clan, tribe, group, whatever that "speaks" to me, but not this time. Kinda left me feeling like the White Wolf-esque clan approach worked against the game instead of for it this time.
Smallville High School Yearbook by Margaret Weis Productions: A fantastic resource for not only refocusing your Smallville games for a high school setting, but a great snapshot of "TV American High School". In fact, if you have the extra money and are running any kind of game set in modern American high school and need a refresher on things, I'd recommend picking it up.
WHY IT DIDN'T MAKE THE TOP SIX: In this case, I think the focus was specialized enough that if it were a complete game (like Tough Justice), I would have given it a nod. I couldn't quite do that given that it's a very specific (though well written) sourcebook for another game. Fantastic book, limited in scope, but incredibly useful for that scope.