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