Genre: heavy metal (with some progressive tendencies)
Don't let the cover art fool you - this is not a black metal album or a doom metal album or a gothic metal album. "Book of Kings" is a melodic 1990s heavy metal release, and it's not bad at all.
The introduction, I think, is kind of a pointless filler, and the first real song "Deadringer" should perhaps have been called "Deadbeat", because it is not really that interesting. But once the listener has successfully gone past those hurdles, he or she will be rewarded, because the remaining tracks on the album are full of interesting stuff. Actually "Voodoo", "Bullet's that Day", "Landin' Space", and "Fool of Dreams" constitute somewhat of a streak, as they're all good and solid tracks. Most of the songs on this album are, while drawing on the metal of the 1980s and 1990s, slightly progressively inclined, as they contain chords that are unusual in metal, some guitar riffs that are alightly odd (such as the main riff of "Fool of Dreams", and also some interesting rhythmical variants on the 4/4 pattern (mostly it's straight rocking drums though).
The production annoys me a bit, as Akira's guitars lack substance and bottom, I think, and the massive amount of reverb makes it difficult to hear all the details of his playing, which is a shame since he does some interesting and cool things. Also, the last track is a drum solo which to me really just seems like a filler. I'd prefer a song or two more on the album than a drum solo - but maybe drummers will appreciate it.
I would recommend this album to fans of traditional heavy metal, prog metal fans might also like it, and I can imagine that some fans of power metal would appreciate it too.