Here is the full list of all 31 HammerHelm achievements.
Destroy a necromancer
Craft a full set of blood stone armor
Craft a full set of diamond armor
Craft a full set of gold armor
Craft a full set of jade armor
Imbue a weapon using a gem
Place a weaponsmith and an armorsmith
Place 4 stone towers
Place 10 houses
Craft a full set of iron armor
Place a sewer entrance
Place a brewery and assign a brewer
Place a fishing pier and assign a fisherman
Have a carpenter and 3 fully furnished homes
Place a stone entrance
Destroy monsters in a dungeon
Place a farm and assign a farmer
Spend 5 skill points
Destroy 4 monster camps
Craft a shield
Place a water well
Have a Stomemason craft a fireplace
Chop down a tree
Meet Shaydee the Goblin
Craft a full set of copper armor
Meet Grrrumble and learn his story
Clear monsters from a cave
Craft any weapon
Craft a healing potion
Mine three ore rocks
Place a house