Here is the full list of all 36 Happy Wars achievements.
Complete every Story Mission
Play 100 non-tutorial games
Complete the 'The Godlike Swordsman' Quest
Reach rank 20
Get a Level 10 item
Unlock the
Launch a Team Skill and get a kill in a Quick Match or Co-op Mode
Complete at least 20 Quests
Use Warrior, Cleric, and Mage 2 times each in a Quick Match or Co-op Mode
Modify an item and add a buff to it
Level-up an item
Complete all of the tutorials
Get a premium item
Get 15 items
Get 1 win in Co-op mode
Use a talk or order commands 4 times in a Quick Match or Co-op Mode
Receive mention in Hero Pop-up in a Quick Match or Co-op Mode
Get 1 win in Skirmish Mode
Get 1 victory in any game session
Play the Happy Spinner
Use all skills in a Quick Match or Co-op mode
Complete more than 40 quests
Reach rank 40
Reach rank 50
Raise the level of an item to Level 15
Complete at least 60 Quests
Complete the 'Archangel' Quest
Complete the 'The Devil' Quest
Choose Berserker, Engineer, and Zephyr at least once in Quick Match or Co-op mode.
Kill foes with the Berserk skill in Quick Match or Co-op mode at least 100 times.
Kill a foe with the Repair skill in Quick Match or Co-op mode.
Successfully use Wind Swap skill in Quick Match or Co-op mode 50 times total.
Successfully use Ultimate Weapon team skill in Quick Match or Co-op mode 50 times total.
Successfully use Cyclone Rush team skill in Quick Match or Co-op mode 50 times total.
Successfully use Multiple Missile team skill in Quick Match or Co-op mode 50 times total.
Successfully use Gatling or Rocket Launcher in Quick Match or Co-op mode 100 times total.