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