[TheRapingDragon]

Is that the first time you've listened to Opeth? There's a reason that album sounds like it does. At that time in their career they had released 5 albums of progressive death metal and Mikael Åkerfeldt wanted to move the band away from metal. So they recorded two albums at the same time: Deliverance (to appease the fans) and Damnation (to test the waters so to speak). Damnation was the light stuff whereas Deliverance was the heaviest stuff they had ever written.

After that, they continued mixing more progressive elements into the metal until, at this point in time, completely abandoning metal. It wasn't so much that they were 'attempting' a different genre at the time as much as they were 'purposefully trying to shift their entire sound in that direction and didn't want to alienate all their fans'. It still ended up pissing off a lot of fans but Åkerfeldt explained his reasons why (when asked if he would make music like they did at the start of their career):

"It's impossible for us to do that, and quite frankly I would think of it as boring to be in a band that plays just metal music. We're not afraid to experiment, or to be caught with our pants down, so to speak. That's what keeps us going."