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