Yggdrasil is a co-operative game in which players are different Gods of the Norse mythology : Odin, Thor, Tyr, Frey, Heimdall and Frejya. Monsters, the wolf Fenrir, the huge serpent Jormungand, the Fire Giant Surt, the Godess of the Dead Hel, the traitor Loki and the cosmic dragon Nidhogg are moving forward in Asgard inescapably and announce the impending coming of chaos and destruction on the world tree Yggdrasil.