Fenriz from Darkthrone formed this side project called Isengard back in the late 80's, about the same time as Darkthrone formed actually. And much like Darkthrone it started out as a Celtic Frost type of death metal meets black metal band. This can be told from listening to Chapter Two of this cd which features an early demo from 1989.
Isengard evolved along with Fenriz (he being the only member as far as I know) and by 1993 and the EP titled Vandreren which opens the cd, he had evolved the band to a Burzum sound. This is interesting for the same time Burzum leader Varg Vikernes also contributed most of the lyrics to Darkthrone's cd Transilvanian Hunger. Also at around this time Varg killed Mayhem's leader Euronymous, meaning that at this time Fenriz and Nocturno Culto were essentially making friends and even emulating musically the man who killed their old mentor and converter to the black metal style. Very interesting indeed. Also what is interesting is how well Fenriz does this stuff.
On "Chapter One - Vandreren" we find Fenriz moving from slower style almost Viking Metal to Celtic Frost sounding songs (like number 4, "Dommedagssalme"). To a song that sounds alot like later keyboard only Burzum (namely number 5, "In the Halls and Chambers of Stardust The Crystallic Heavens Open". Altogether what we find is an excellent, well played, and surprisingly interesting series of tracks that end with Fenriz burping. Fenriz actually sings and growls pretty well, and he plays guitar pretty well too. And as always his drums are excellent.
"Chapter Two - Isengard Demo (August 1989) - Spectres Over Gorgoroth", finds the band playing quite like Darkthrone's albums Panzerfaust and Total Death. This is dark heavy, sometimes fast, sometimes extra slow, Celtic Frost/Hellhammer style black metal. I like this alot, the songs are quick and the whole demo section is only maybe 15 minutes long, if that. I think it helps to understand Fenriz' and essentially Darkthrone's roots, and then their future as well in many ways, though that future was many years ahead in 1989.
"Chapter Three - Horizons" is a collection of 4 songs recorded at various times. The first song here, "The Fog (Early 1991)" is excellent, being very chaotic slow black metal. The others are good too, with the final one "Our Lord Will Come" being a kind of almost Christian Death style song.
I've heard this described as "folk metal", and in many ways it is. This is Fenriz' folk metal/Viking metal and sometimes ambient side solo project. It is both similar and very different from Darkthrone (think more different than similar though). I highly suggest this for any fan of Darkthrone, it offers an interesting side note in black metal history, and perhaps a little light shed, and some more questions, concerning Darkthrone and Varg's relationship. Excellent album.
Chapter One - Vandreren (1993)
2: Gjennom Skogen Til Blaafjellene
3: Ut I Vannets Dyp Hvor Morket Hviler
5: In the Halls and Chambers of Stardust The Crystallic Heavens Open
6: Fanden Lokker Til Stuper (Nytrad)
Chapter Two - Isengard Demo (August 1989)
Spectres over Gorgoroth
8: Thy Gruesome Death
10: Rise From Below
11: Dark Lord of Gorgoroth
12: Trollwandering (outro)
Chapter Three - Horizons
13: The Fog (Early 1991)
14: Storm of Evil
15: Bergtrollets Gravferd
16: Our Lord Will Come