The show stars two brothers who discover they're modern-day incarnations of the Norse gods Thor and Loki, going up against a family of evil, superpowered Jötunn in their town. Season 1 must have been an immediate hit, because Netflix announced a second season just five weeks after it came out.
Netflix also released some fun graphics spelling out "Oh my god," showing the main characters' supernatural alter-egos in their shadows.
Ragnarok is kind of a surprise hit: a Norwegian-language drama with a relatively unknown cast, and no particular promotional push from Netflix. It may well have benefited from an audience familiar with the Marvel franchise, were modernized versions of Thor and Loki also play a major role.