Yggdrasil is a co-operative game in which players are different gods of the Norse mythology: Odin, Thor, Tyr, Frey, Heimdall and Freyja. Monsters, the wolf Fenrir, the huge serpent Jormungand, the Fire Giant Surt, the Goddess of the Dead Hel, the traitor Loki and the cosmic dragon Nidhögg are moving forward in Asgard inescapably and announce the impending coming of chaos and destruction on the world-tree Yggdrasil. Together the players have to resist to the impending coming of the Evil forces in Asgard, the gods' world.

Game flow
During his turn, the active player first draws an Enemy card, corresponding to one of the six Evil creatures. The corresponding counter is moved one space forward in Asgard and the associated effect applies. Then the active player performs three different actions among the nine at his disposal in order to resist to the advance:

• Ask for the Elves' help
  
• Get (or improve) a Weapon from the Dwarves
  
• Send the Valkyries looking for Vikings' souls on the mankind world of Midgard
  
• Fight the Fire Giants and try to gather the parts of a magic rune
  
• Negotiate with the Vanir
  
• Get rid of the Fire Giants who invade Midgard
  
• Get the Vikings back from Hel's world
  
• Exchange forces with another god
  
• Fight against the Enemies in Asgard