Full list of all 96 UnderMine achievements.
The base game contains 94 achievements, and there is 1 DLC pack containing 2 achievements.
Defeated Seer, World's Heart
Defeated Seer, World's Heart without upgrades
Entered the Golden Core
Entered the Golden Core before defeating Ponzu
Died 100 times
Lifted the Summoning Stone 30 times
Found all 3 dogs in the UnderMine
Rescued Kurtz
Spent 100,000 gold at shops
Spawned a secret shop, in a secret shop, in a secret shop
Held 99 keys at once
Died with an Elixir in your inventory
Learned 10 new blessings
Crafted 10 new potions
Fully upgraded the pickaxe
Lifted the Summoning Stone 10 times
Fully upgraded the bombs
Held 99 bombs at once
Transmuted 3 Relics at the same time using Transmutagen
Thwarted 500 pilfers
Spent 50,000 gold at shops
Died 50 times
Peeped 100 skeletons
Fully upgraded the tunic
Crafted 30 new relics
Discovered the Golden Idol
Stole an item from the shop
Crafted 20 new relics
Completed 3 runs of Othermine without dying
Completed an Othermine run without upgrades from the antechamber chest or shops
Defeated Ponzu, Scaled Assembly without upgrades
Defeated Noori, Spectre of Darkness without upgrades
Defeated Mortar, Charged Golem without upgrades
Entered the Halls of Din before defeating Mortar
Defeated Selt, Lord of Sand without upgrades
Completed a run of the Othermine
Fully expanded the potion slots
Crafted 10 new relics
Held 3 of the same potion at the same time
Lost 5,000 gold to pilfers
Defeated a Hoarding Pilfer
Entered the Delvemore Dungeon before defeating Selt
Fully upgraded the gloves
Bought every item in a fully expanded shop
Completely expanded the Pilfer shop
Defeated Selt, Mortar, and Noori with the same peasant
Spent 10,000 gold at shops
Discovered the Othermine
Fully upgraded the goldsack
Lifted the Summoning Stone for the first time
Defeated Ponzu, Scaled Assembly
Entered the Shimmering Caverns
Defeated Noori, Spectre of Darkness
Peeped 10 skeletons
Completely expanded Dibble's shop
Had 6 curses active at the same time
Expanded the potion slot once
Fully upgraded the counter weight
Had something popcorn 5 times in a row
Healed 1,000 hp using food in one run
Learned a new blessing
Died 10 times
Crafted a new potion
Rescued Dibble
Assisted Beltrame
Crafted a new relic
Entered the Halls of Din
Defeated Mortar, Charged Golem
Ate cooked food for the first time
Cleansed a curse for the first time
Rescued Lillyth
Defeated the Dungeon Gargoyles
Destroyed 20 signs
Joined the Pilfer Loyalty Program
Entered the Delvemore Dungeon
Defeated Selt, Lord of Sand
Put yourself out in water
Discovered a secret floor
Met Black Rabbit
Rescued Dodson
Defeated the Rockpile Mimic
Discovered a secret room
Rescued Wayland
Completed a run with at least 2 hexes