Full list of all 96 UnderMine achievements.
The base game contains 94 achievements, and there is 1 DLC pack containing 2 achievements.
Entered the Delvemore Dungeon before defeating Selt
Bought every item in a fully expanded shop
Fully upgraded the bombs
Fully upgraded the tunic
Fully upgraded the gloves
Held 99 bombs at once
Rescued Kurtz
Fully expanded the potion slots
Died 50 times
Fully upgraded the pickaxe
Fully upgraded the goldsack
Discovered the Othermine
Lifted the Summoning Stone for the first time
Defeated Seer, World's Heart
Defeated Ponzu, Scaled Assembly
Crafted 30 new relics
Completely expanded the Pilfer shop
Entered the Golden Core
Entered the Golden Core before defeating Ponzu
Thwarted 500 pilfers
Peeped 100 skeletons
Lost 5,000 gold to pilfers
Stole an item from the shop
Fully upgraded the counter weight
Had 6 curses active at the same time
Spent 100,000 gold at shops
Completely expanded Dibble's shop
Healed 1,000 hp using food in one run
Entered the Shimmering Caverns
Defeated Noori, Spectre of Darkness
Crafted 20 new relics
Crafted 10 new potions
Expanded the potion slot once
Defeated a Hoarding Pilfer
Spent 50,000 gold at shops
Learned a new blessing
Learned 10 new blessings
Found all 3 dogs in the UnderMine
Crafted 10 new relics
Entered the Halls of Din
Defeated Mortar, Charged Golem
Rescued Lillyth
Defeated the Dungeon Gargoyles
Cleansed a curse for the first time
Spent 10,000 gold at shops
Rescued Dibble
Joined the Pilfer Loyalty Program
Entered the Delvemore Dungeon
Defeated Selt, Lord of Sand
Ate cooked food for the first time
Crafted a new potion
Had something popcorn 5 times in a row
Peeped 10 skeletons
Died 10 times
Crafted a new relic
Put yourself out in water
Destroyed 20 signs
Assisted Beltrame
Discovered a secret floor
Met Black Rabbit
Rescued Dodson
Defeated the Rockpile Mimic
Discovered a secret room
Rescued Wayland
Entered the Halls of Din before defeating Mortar
Died 100 times
Held 99 keys 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
Transmuted 3 Relics at the same time using Transmutagen
Held 3 of the same potion at the same time
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
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