I do not recommend this game in its current Early Access state as of 11/17/2014.
A) I will begin by addressing the achievement awarding system in this game, since I cannot find another reviewer who has. A lesser problem, perhaps, but still worth talking about, as the achievement system is very unusual to say the least. In-game, it'll keep displaying a screen reminding you every time you complete an achievement even after you have gotten it already. It gets annoying after a while. Also, unlike other Steam games, the achievements register in your Steam account only after you exit the entire game, even when you're playing it in online mode (as opposed to achievements you get while offline being credited only when you switch back online, all at once), so you'll be getting multiple achievements with the exact time stamp. E.g. If you beat Peasant, Farmer and Artisan difficulties in one session, their achievements will register in your Steam account, after you exit the software, with the exact same time and date as if you beat all three difficulty levels (three separate games) at exactly the same minute.
If there are ways to get the achievements to be credited/registered in your Steam account without closing the entire game, please do tell. EDIT (11/25/14): I found that it triggers achievements unlocked through single player into your Steam account if you switch to online multiplayer (for reasons unknown) after getting those achievements, without closing the entire software.
B) The game gliches out and crashes often, making it frustrating to finish a game unless you repeatedly click Save and Exit and resume the game (it does not have a save only function, so every time you save you have to exit the game as well). The game usually crashes soon after a piece turns completely back.
C) The second puzzle in the Hard section of Skill Challenge, "Dynamic Duo," is and should be impossible to solve. It says to checkmate the King in five moves, which is only possible if the computer makes a mistake on the second
move (which it does for some reason if you set the PvC difficulty to Clergyman or below after clicking on "New Game" button, which makes absolutely no sense since the Skill Challenge is completely independent and separate). With the best play by the computer, there's no way you can checkmate the King in five moves. It is not customary for chess problems to expect the player to assume that the opposition in the puzzle might
make an error (for those who don't know).
D) The computer moves extremely slow in Monarch difficulty relative to the rest of the levels, even on obvious recapture moves (I also tried the Fool's Mate just to see how long it would take the computer to play 2... Qh4 and checkmate me. Guess what, it took at least over a minute every single time. It is silly.) However, that doesn't mean that it's easy. Monarch difficulty is a big jump from Clergyman (the second highest difficulty level), compared to, say, from Farmer to Artisan or Nobleman to Clergyman, so there is a large imbalance in level design. It's much harder to beat. To defeat Monarch, you'll need to be a relatively strong chess player.
E) Besides adding a save function without having to exit the game simultaneously, I think a draw offer option in singler player would be nice, too, as most other chess programs have it.
Of course, these are not all of the problems that exist in the current Early Access version (as you can see by reading other reviews), but just the ones I felt the most important to address.
All that being said, I strongly believe that Battle Chess: Game of Kings
has a lot of potential to become a very good game. I sincerely hope the developers will be able to fix all of these problems (and more) in the not-too-distant future.