Here is the full list of all 20 Völgarr the Viking achievements.
Complete the game and earn Ending C
Complete the game and earn Ending B
Hitch a ride on a spear attached to an enemy shield
Complete the game with 10 or less retries (deaths)
Complete the game and earn Ending A
Reach Yggdrasil's roots
Kill Fafnir before he reaches his Dragon form
Break the Magic Seal on Fafnir's Tower
Find a Key Stone
Unlock Mjolnir's power
Reach the alternate path for any world
Obtain a Warrior Spirit
Complete any world in 4 minutes or less
Complete any world without ever losing any equipment
Collect a golden walrus statue
Defeat the Lizardmen King
Block an attack with the shield while on a rope/chain
Wield the fire sword
Kill 4 enemies with a single charged spear attack
Block a projectile with the shield while in the air