I found 32 open-able doors in the game, although only 26 are used for the achievement. I don't know which ones they are, so it's best to do them all. I mention this because it seems to be the hardest achievement for everybody. Anyway, enjoy the game!

1st Note: Missing Dad
When you first start the game, turn around and walk towards the red car. Just past that is the tree house. If you pass the tree house you find the ramp to go inside. The note is to your left on the table.






1st Item: Dead Magpie (Asekladden & the Princess):
Look to the left from where you found the first note and the bird will be lying on the ground.
Afterwards, return to the original path down to the pier to continue the story.






2nd Note: From Espen
Once you wake up as Karen, this note will be directly across from you on the counter.

3rd Note: Shopping List
From the second note, look right; this note is a yellow sticky note on the refrigerator.

• 1st Dwarven Gate 1/14:
  When you get control on the pier, follow the path a little bit and there will be a path to the left. Follow this path all the way up to the first Dwarven Gate.
  
  
  
  
  
  
• DOORS*
  There are 3 doors in the village before the Mead Hall's double doors that you have to open to progress. Actual "Press E to Open" doors. I'm not going to list them all, but a little exploring will get them.
  
  
  
  
  
  
• Item: A Ram's Horn, (Askeladden & the Princess):
  The horn is sitting in a cabin on a table. Once you enter the cabin, follow the wall to your left 180 degrees and you will see it.
  
  
  
  
  
  
• 1st Villager Tales: Old Erik
  Inside one of the cabins, on the table as you enter the door is an open book.

Once you have all of these, proceed to the Mead Hall (the big house) at the top of the hill. The double doors count towards your achievement, and are the fourth doors of the level. There's nothing to find in the hall, except perhaps some cool screenshots.

• Door (5)
  Once you're through the building and out on the other side, take the path to the left, the second cabin on your left has door #5.
  
  
• Note: Rakker
  IN THAT SAME CABIN as door #5, once you enter there is a sheaf of paper on the table. Collect the note.
  
  
  
  
  
  
• Door (6)
  Turn around and go back to the Mead Hall, and take the right path to the first cabin for door #6.
  
  
  
  
  
  
• Door (7)
  Continue on the path to the gate hut. BEFORE YOU ENTER, look left and you will find a set of steps. Go up these steps, and to your right is the last door, #7. Stay there.
  
  
  
  
  
  
• Item: A Ring of Birch, (Askeladden & the Princess):
  From Door 7, continue through the second door at the back of the room and you will find yourself on a balcony, look left at the bench and you will see a rope-looking stand. Collect it.
  
  
  
  
  
  
• 1st Reflector: Snowman
  Go back downstairs and enter the gate hut. On the table is the reflector. Can't miss it, it literally glows in the dark.

Gathered Norway to One Kingdom:
Once you gain control start walking down the path until you reach the glowing save stone. After that, take the path to the right and follow it as far as it will go, keeping the water to your right. Soon you'll reach an area where you can see 3 LARGE swords sticking out of the ground on your right. Walk up to them for the achievement.





2nd Dwarven Gate:
From the three swords, turn around and go straight until you reach a light brown branch with a white rock behind it. Behind this is a little cave which you need to enter. Continue all the way through and crouch down through the end and you'll be in the troll's cave. You just passed through the gate, you can turn around to see it's ruins.





2nd Villager Tales: TROLL!:
Once you've passed through the second dwarven gate, turn to your right and you'll see a bloody skeleton on the floor facing you. On a rock behind their head is a note.





3rd Dwarven Gate:
From the note in the troll's cave, continue on out of the other exit, passing the fire on your right, and climb up the hill path to the right. Where the path forks at the sign, go left and follow the path continuously left until it ends in the Gate.





3rd Villager Tales: Nokken:
Go back to the fork in the road and follow the right path. Keep on the trail for a long while (there will be an audio monologue) and you'll eventually come across a cabin by a lake. Enter the cabin and across from the door is a note on a stool.




Other Tales: Troll's Spatula:
When you exit the cabin, look to the rest of the trail and you'll see a large rock with a shield in front of it. Walk to the right of the rock and up the path and you'll see a huge door with light coming out of it. Go inside and the Spatula is on the floor in this room.




2nd Reflector: SQUIRREL:
Go back to the main path and follow it to a small wooden bridge. The reflector is hanging on the right. Glowing bright green, can't miss it.







Thursvik Niflung:
From the bridge with the reflector, continue on the path until you see a camping area on your left hand side. Just past it, near the water, are some stacked rocks with a bundle inside. Click on the bundle to reveal a child's remains.




Note: The water! The water! Something in the water!:
Follow the main path onward until you reach a gate across your path. To your right is a blue save stone. On a rock in front of the stone is a note.






9th Door:
Go through the gate and take the path up the hill to the right. Open the door on the cabin to the right.








1st Item: Wedge (Askeladden & the Princess):
Once you enter that cabin, there is a cupboard/cabinet on the right. Go around it's corner and the Wedge will show up on the surface.






10th Door:
Exit from that cabin and enter the cabin across the path.







2nd Note: I'll Be Waiting:
As you enter that same cabin, on the table across from the door is a note.








11th Door:
Go outside and follow the path to the left, it circles around back to the main path. Enter the cabin on the opposite side.






3rd Note: To Ingrid:
Once you're inside that cabin, there is a note on the table to the left of the door.








Continue on the main path, over the bridge until you get to the loading point. The screen will fade out.

Fosborg Niflung:
From the beginning, follow the main path until you come across a path to your right going up the hill with wooden boards/stairs. DON"T GO UP YET. Follow the trail to the left, into a secret cave, and at the back of the cave to the right, you'll find another child's remains.




Continue on the main trail, up the wooden steps, and you'll reach an area with another troll. You can try to sneak past him OR There's a path to your left that will bring you all the way around, through his cave with the fire, and out to the end of that area. Just make sure that he walked away from the exit first!


4th Dwarven Gate:
Once you're past the troll, continue following the main path and the Dwarven Gate will be on the left side. Can't-miss it.







12th Door:
Opposite from the Dwarven Gate is another stone path, this time going steeply up the hillside. At the top is a cabin; open the door.







13th Door:
Go back to the main trail and follow it. Soon there will be a cabin on your right. Open the door.







1st Hird Note: Hird Notice, WARGS:
Walk into the village and look at the statue. The Notice is pinned to the statue.







14th & 15th Door:
The 14th door and 15th are located on the cabin directly behind the statue. There are 2 doors in this cabin. First, go right and around to the door. Then come back and follow the main path for a couple of feet and turn right into the cabin's yard. Open the door.







16th Door:
There are too many doors... Continue on the main path. At the cabin where the path ends will be a conversation between Karen and an unknown individual, after which, the cabin starts burning. Go around the right side of the cabin and go down to the next cabin. Open the door.





Villager Tales: Missing Daughter:
Once inside that last cabin, look right and on the table is a book.







17th Door:
Stay on the path down the waterfall and you'll run into a crazy man holding a baby's corpse. Open the door to his cabin.







Pottery Shard (Askeladden & the Princess):
Inside that same cabin, explore to the left and on the table is the shard of pottery.








3rd Reflector: Car Logo:
Keep on the main path past the crazy guy till you reach the rickety bridge. The reflector will be glowing bright blue on the right side of the bridge. Picking it up will give you the Breadcrumbs achievement.







Other Tales: Veslefrikk:
AS SOON AS YOU STEP OFF THE BRIDGE, take a HARD left and follow the water into a hidden cave. At the back of the cave is a violin/fiddle on top of a rock.







Villager Tales: Feast & Death:
Come back to the main path and take the white stone steps up the hill to your left. When you come to the fork in the road, turn left again and follow it into the large dilapidated building full of dead people. Before you exit through the back, enter the door on the left and on the table, next to the slumped over dead woman, is a page.





18th Door:
Once you exit the last building, there is a hut on the other side of the path. Open the door.








19th Door:
Go back on to the path, to the left until you reach the gatehouse. There is another somewhat hidden stairwell on the left side of the house. Go up the stairs and open the door.







2nd Hird Note: BEWARE:
Go back down and enter the gatehouse. Just before you exit through the outer door there will be a page on the wall.
ALSO 19th Door: Right next to it. Unmissable.






I Scream, You Scream & Among the Sleep:
After this is the HULDRA monster, preceded by a save stone. (Thankfully cause I suck) This is also the best time to get the "I Scream, You Scream" by allowing her to kill you, and "Among the Sleep" achievements by allowing her to kill you 10 times.

5th Dwarven Gate:
After the Huldras and the load screen, walk down the path to the first right. Take that rightmost path until you reach this next Dwarven gate on your right. Continue on the path.
CAUTION: For those who haven't played before, after this you have to escape the Huldra again. Once you have PASSED over the bridge and through the gate, you're safe.





20th Door:
Once you've passed the Huldra area and followed the path through the cabin, continue up the slope. At the top is a save stone and a cabin. Open the door.






Villager Tales: The Screaming:
Enter the cabin and turn right. On the table is an open book.








21st Door:
Continue up the main path to the next cabin, on your right. Open the door







Erik's Tale #1: The War:
Once you've entered the last cabin, go through to the left and on the table is a page.







22nd Door:
Keep going up the path. At the top of the hill is another cabin on the right with double doors. Open them.







Villager Tales: The Brothers Are Trapped 1:
Inside the cabin you just opened and on the table across from you is an open book.









23rd Door:
Follow the path until it forks, then follow the right fork down. At the bottom is a lone cabin, follow it around to the far side. Open the door.









Copy of A Ram's Horn (Askeladden & the Princess):
Inside this cabin is another copy of the Ram's Horn from Askeladden & the Princess. Take it if you need it.








24th Door:
Go back up to the fork and continue up the path to the gate. Once through, enter the right cabin.









Villager Tales: The Brothers are Trapped #2:
Inside the cabin that you just opened, on the table, there is another paper.








A Plague Upon Both Your Houses:
Go a little further down the road and on the left is a gate. Walk up to the gate to see Pesta The Plague Maiden on the other side for the achievement.







At the top of the hill is a save stone....so you know what that means. Another monster to contend with. This time it's a boar from hell. Die by the boar for an achievement. Spoiler spoiler: Instead of messing with the boar AT ALL, you can veer right and enter the cave area with the candle. This will lead you to a long and winding trail on the mountainside that will bring you to the exit. Once there, turn around a walk back towards the boar to the cabin.


25th Door: (I hate life now)
Once you've passed the boar, one way or another there's a cabin. The boar shouldn't chase you once you've made it. Open the door and stay.






Other Tales: Seventh Father:
Upon entering the boar cabin, you'll notice a hunting horn on the wall. Pick it up.







Villager Tales: The Boar:
Inside that same previous cabin, on the bed, is a page.









Item: ANOTHER Ram's Horn:(Askeladden & the Princess):
Keep going on the main path over the bridge and up the hill until you either hear a weird sound or SEE THE HUGE GLOWING EYEBALL IN THE ROCK. To the eye's right, and up the little hill is the ram's horn.





At the top is a small save stone. Spoilers for 1st timers: There is a troll on the path. When he's fighting the other troll, hide behind the right side of the boulder on the path. After they're done fighting, he will walk past you, wait a couple seconds for him to walk away and then continue on.





6th Dwarven Gate:
Once you're past that and past the sword graveyard, you will see another Dwarven gate behind some trees to the left of the path. Can't miss.






7th Dwarven Gate:
Can't miss it, you have to walk through it to progress.







8th Dwarven Gate:
STOP! Once you've passed the loading screen after going through the last Dwarven gate, stop, turn around, and go back. This closed side of the gate counts as the 8th gate. Don't ask why, idk.








Toy Soldiers:
Continue on till you reach Erik's cabin and turn left into the wolf cave. Follow the cave all the way to the end into the toy chamber for the achievement.






Registry of Little Heroes:
NOT NEEDED but interesting Kickstarter add-on in the middle of the toy chamber.







Erik's Journal 1/3: The Children:
In the toy chamber, on the ground, to the right of the statue, is a paper.









26th Door:
Go back out and enter Erik's Cabin.










Erik's Journal 2/3: Bifrost:
After the cutscene, look at the workbench in the corner (to the right when facing the door) and there will be 2 books and a small post-it note that says 665.

Erik's Journal 3/3: Somewhere Else
This is the second book on the workbench.





Other Tales: Gate Key:
On the table in the middle of the room is a large key. Take it.








27th Door: (why?)
Go back outside, turn right, and walk up to the shed. The lock is from the code inside, the old man was not very smart. Open the door. 665







Erik's Tale: The Wolf:
Go inside the shed and on the right hand table is a paper.










28th Door:
Go back outside to the path and turn right. The double gates are the last doors.








9th Dwarven Gate:
Go through the gate and follow the path all the way to the end for the last dwarven gate. Then turn around and come back towards the cabin area, head left down to the strange lighting to end.

Reidving Niflung: Mist Children 3/4:
Once you start playing again, follow the trail down to the open area where Erik throws a torch at a wolf. Take a hard right and there will be a cave; go through and across the wooden bridge. After the bridge, turn right and ascend the slope, the child's remains will be at the top left under some stacked stones.






10th Dwarven Gate:
Can't miss it, you have to run through them to progress. I advise running through them, the black wolf will eat you if you don't.






Red Raiding Hood:
Continue all the way down to right before the floor of the valley. You'll know you're there when the blue stone lights up on your right and the white wolf says: "I see you". Use your flashlight to freeze or burn him, then run into the cave at your right. He won't follow you in. At the back of the cave is the red hood, the tree man will be on your left. For me, it REALLY glitched out so I couldn't see it, but still got the achievement.







11th and 12th Dwarven Gates:
DWARVEN GATES #11/#12: Located inside the temple, while you're fending off the wolves. Starting on the stairs: In the back right corner of the temple is a round room with two dwarven statues outside of it; run through the room. ALSO, along the back wall of the temple, in the middle behind the BIG main dwarf statue is another gate with broken doors. Make sure you see/pass this one too.







13th Dwarven Gate:
Once you've gotten around the temple and up the stairs to where the wolves are talking with you. You're trapped against the door. Thats the one.

14th/ LAST Dwarven Gate:
At the start, follow the trail down to the gate. Stop, look right, and walk up to it. You should get the "It Only Counts As One!" achievement.







The Hird 3/3: The Veiled Lady:
On the gate, pinned to the left, is a piece of paper.










29th Door:
Go through the village, drop down through the cabin onto the lower path, and the first cabin on your left will have a door. Open it.








30th Door:
The next cabin on the right. Open it.








Villagers Tales: Bjorn
Inside that last cabin, on the table, is a paper.









31st Door:
Cross the path to the next cabin, open the door.









Erik's Tale: The Pact:
Inside this cabin, on the table, is a paper.








32nd (Last) Door:
Take the path all the way down to the mire, the save stone should glow next to you. Take the path to your left, up to the single cabin. Open the cabin door. At this point you should receive the achievement.







Villager's Tales: Down in the Mire:
In that lone cabin in the mire, on the table, is a paper.










I Didn't See Dead People:
At this point in the swamp, go up to one of the draugur "zombies" and let it kill you for the achievement.







Shoe Sole: (Askeladden & the Princess):
Exit the cabin and face the way you just came. You'll see the main path leading down and then another path leading right. Take the path to the right all the way until you reach a small pier. The sole is at the end of this.







Vidarby Niflung: Mist Children:
Go back to the save stone and the main road, follow it's winding way all the way to the back of the level, past the fork in the road (go right), and past the next save stone. After this, at the top of the hill, the Veiled Lady will fly out of a cave in front of you. Turn right, into the cave and down the steps. There's a dead woman on the bottom left holding the baby. At this time you should get the "Left For Dead" achievement.






Good Dog:
Go back out of the cave and continue on the path. At the bottom of the hill is the great hound, Garm. He asks you to kill him. He tells you to kill him. Kill him for the achievement.

Erik's Tale: Sacrifice 1:
Follow the main path until you reach the large building on the hill. Go inside, turn to the left, and on a stone on the ground is a paper.







Erik's Tale: Sacrifice 2:
Continue through the building, through the courtyard, and into the hallway. Halfway down, on the ground, to the right, and next to a candle, is the paper. You should receive the "My Mom is Smarter Than Yours!" achievement.





He Started it All:
Continue on the path until you come up to the huge impaled ribcage. Past the ribcage, on the horizon, to the right, is a giant save stone with a hole in the top. Go up to the save stone and walk around it to see Vidar.





Bifrost Key (Other Tales): Automatically earned at the end.
Erik's Keys (Other Tales): Also earned at the end.

By this time you should have earned EVERY achievement. Don't forget that you have to die to every creature as well to 100% the game, and die at least 10 times total too. Don't be afraid to rate, save, or comment on this guide, and if I messed up somewhere send me a message. Best of Luck!