Here is the full list of all 33 Zombie Vikings achievements.
Finish the story!
Strike a frozen enemies back and forth 10 times
Have Beaknose defeat 10 enemies
Catch the same enemy three times without them touching the ground
Keep an enemy airborne for 4 seconds
Kill 3 heavy enemies at the same time
Kill an enemy with their own projectile
Kill an enemy by throwing a chicken at them
Have 6 enemies stunned at the same time
Revive a friend by throwing both parts into each other mid-air
Defeat an enemy by throwing a friend's head into them
Make an enemy bounce on 4 others
Have all players hold an enemy before it touches the ground
Get revived 50 times
Have the crushers defeat 10 enemies
Clear the Tavern Brawl in Richside unscathed
Hit a frozen enemy into 5 other enemies
Win a duel to the undeath
Defeat a boss with zombie vomit
Perform the 4 player charge attack on the stitch zombie
Find the super secret developer area
Form a zombie tower of 5 with a guest of your choice
Escape the fishturd cannon unschathed with 4 players
Win against the Butterflies in Söcker without letting the other team score once
Complete the secret Fe dream sequence
Complete the gnome cave without ever being detected
Spend a total of 30.000 gold in the store
Defeat the Common Cold without hitting him with your sword
Finish the Berzerker Factory without one player touching a conveyor belt
Unlock all weapons
Unlock all runes
Complete all sidequests in the game
Open 25 chests