Here is the full list of all 42 Hammerwatch Anniversary Edition achievements.
Defeat 25,000 enemies
Acquire 100,000 coins
Survived the Sun Temple on Serious difficulty
Defeat Sha'rand the Sun Guardian on any difficulty
Enter and exit the Pyramid of Fear
Upgrade a shop to maximum in the Sun Temple campaign
Defeat Worldfire the Red Dragon on any difficulty
Complete all the bonus levels in Castle Hammerwatch
Reach a count of at least 500 in a single combo
Defeat the Arch-Lich on any difficulty
Defeat the Fallen Knight on any difficulty
Defeat the Stone Golem on any difficulty
Rescued the apothecary in the mines.
Defeat the Maggot Queen on any difficulty
Find a bonus level in Castle Hammerwatch
Find a plank
Escaped the destruction of Castle Hammerwatch on Serious difficulty
Escaped the destruction of Castle Hammerwatch
Defeat the Desert Sharks on any difficulty
Defeat Krilith the Frost Sorcerer on any difficulty
Return the pickaxe to the miner to clear the rocks
Return to the lever to its rightful place to drain the waters
Return the frying pan to its owner
Defeat the Warden on any difficulty
Defeat the Wraith Councilors on any difficulty
Defeat the Watcher on any difficulty
Defeat the Vampire Count on any difficulty
Defeat Thundersnow the Blue Dragon on any difficulty
Escaped the destruction of Shaftlocke Tower
Escaped the destruction of Shaftlocke Tower on Serious difficulty
Fixed all the elevators in the tower
Restored the fountain
Got the ore from the miner.
Help out a miner with a big rock
Release some prisoners and find a treasure
Find the real resting place of the duke
Solve the curious book's code
Solve a dispute over a room
Avenge a fallen magician
Overcome four challenges and find a powerful book
Find a dangerous but lucrative cave in the Mines
Upgrade all the shops to maximum in the Shaftlocke Tower campaign