Its more like a structured sandbox. Think of Terraria or something. There is an "intended" progression path through the game, but how you tackle the challenge is up to you. There are no quests (except the main one where you are Odin's champion basically going after his enemies). There's barely any NPCs. The world is procedural and there are no artificial barriers blocking your path. Neither enemies or the loot are level scaled; you can get yourself in as big of a trouble as you want. There is some lore and backstory, but its not a narrative driven game by any stretch.

When you die, you leave a grave with your belongings. You also lose 5% of your skillpoints in every category. The penalty for dying is not harsh, just something to keep you from mindlessly throwing yourself at an impossible situation.

Oh, I guess its worth saying that building is a big part of this game. If you enjoy building your own fortress or viking settlement in the middle of the wilderness you probably are going to like this game.