OSI are extremely tough to nail down, and that's not just because they seem to have ins with every major progressive band in the books. Jim Matheos and Kevin Moore, the only two actual members of the band, come from such Fates Warning and Dream Theater respectively, and their guest musicians over their career have included names like Mike Portnoy (Dream Theater, Liquid Tension Experiment), Gavin Harrison (Porcupine Tree), and Mikael Åkerfeldt (Opeth) to name a few. With talents like that behind the music, you'd probably expect their work on 2012's Fire Make Thunder to be almost impenetrably complex.
And that's what's most surprising (and rewarding) about OSI: they're musically interesting while still being accessibly easy to listen to. In fact, Matheos and Moore seem to shy away from superfluous displays of musicianship almost entirely. As a result, the progressive elements on Fire Make Thunder are very subdued; you wouldn't even be able to tell they're jamming out in 7/4 on "Guards" and "Enemy Prayers" unless you were paying close attention. It gives the album an unexpectedly chilled-out and laid-back sound. It doesn't sound like the band are restraining anything or are playing sloppily, though. What it does sound like they're purposefully trying to keep everything unnecessary out of the music in favour of artful simplicity and sleekness.
And let me tell you, the music is very, very slick. The main riffs to "Big Chief II" and the instrumental "Enemy Prayers" in particular are perfect examples of how to make a very simple melodic idea go a long way stylistically, and the epic closer "Invisible Men" also has some pretty righteous jams in its ten-minute span (yes, I still use 'righteous' unironically). And these aren't the only moments; every song on the album has something rewarding to offer, without exception. There are no weak tracks.
Speaking of weaknesses, it is clear from listening to the album Kevin Moore's vocal ability and range is limited. However, it seems he's not only aware of the fact, but that he also makes the best possible use of it he can while knowing his own limitations. As a result, the vocals on Fire Make Thunder are almost monotone, but artfully so; rather than trying to force himself into wild expressive ranges, he pulls off this cool, nonchalant variety of singing that sounds apropriate with the rest of the album's slick polish. Some of the lighter pieces like "Indian Curse", "For Nothing" and "Wind Won't Howl" do feel like they could use some vocals with more expressive ability to match their delicate natures, but that's a somewhat minor complaint. In addition, the lyrics aren't particularly interesting, but they fit the generally understated tone of the album with their simplicity quite well.
And, naturally, given the calibre of the talent behind this album, there are naturally a few spontaneous displays of musicianship peppered sporadically throughout the album. Matheos in particular makes his moment on "Enemy Prayers" worth it by busting out into one of his best solos, and Harrison's guest drumming also has some subtle flair to it on tracks like "Guards".
Basically, this album is the perfect example of how to do a lot with a little. Everything about Fire Make Thunder is extremely minimalist but with artful intention, and the result is surprisingly satisfying. Definitely give this a listen.