Since I’m in the country that provides the world with a significant number of extreme rock/metal bands, I should mention one of the popular places where the fans of such genres meet and listen to their favorite artists.
It has a central location, on one of the streets crossing the main tourist street (Karl Johann), right next to one of the subway exists from Strotinget. They often host a concert on the small stage inside – for their schedule check their myspace page. If you go there there on an evening with a concert, the entrance is no longer free. Although there haven’t been many concerts lately.
They have a pool table where you can have fun with your friends. I have seen both cases when the DJ takes requests and refuses them, so I am uncertain about the rule of the house. The bartenders have interesting outfits and metal looks sometimes and it happened that I ran into a musician from one of the local rock bands. Maybe the biggest challenge is to recognize them without makeup and the amount of spikes that they wear at their concerts. Nevertheless, I find it a friendly place where you can easily have a chat with anyone. If it’s too warm inside, they have a couple of tables outside for smokers and you can take the drink outside at any time, a rare thing in Oslo bars.