Full list of all 96 UnderMine achievements worth 1,000 gamerscore. It takes around 80-100 hours to unlock all of the achievements on Xbox One.
Rescued Kurtz
Discovered the Othermine
Fully expanded the potion slots
Lost 5,000 gold to pilfers
Crafted 30 new relics
Lifted the Summoning Stone for the first time
Defeated Seer, World's Heart
Hatched a new egg
Defeated Ponzu, Scaled Assembly
Joined the Pilfer Loyalty Program
Defeated a Hoarding Pilfer
Healed 1,000 hp using food in one run
Fully upgraded the counter weight
Completely expanded Dibble's shop
Crafted 20 new relics
Spent 100,000 gold at shops
Stole an item from the shop
Found all 3 dogs in the UnderMine
Learned 10 new blessings
Learned a new blessing
Defeated Noori, Spectre of Darkness
Spent 50,000 gold at shops
Crafted 10 new potions
Discovered Griswold, the Collector
Entered the Golden Core
Entered the Golden Core before defeating Ponzu
Entered the Shimmering Caverns
Entered the Shimmering Caverns before defeating Noori
Crafted 10 new relics
Expanded the potion slot once
Rescued Lillyth
Defeated the Dungeon Gargoyles
Died 10 times
Peeped 10 skeletons
Raised a familiar to maximum level
Entered the Halls of Din
Defeated Mortar, Charged Golem
Spent 10,000 gold at shops
Discovered a secret floor
Destroyed 20 signs
Defeated Selt, Queen of Sand
Crafted a new potion
Had 6 curses active at the same time
Made a deal with the demon Sho'guul
Rescued Dibble
Entered the Delvemore Dungeon before defeating Selt
Entered the Delvemore Dungeon
Ate cooked food for the first time
Had something popcorn 5 times in a row
Assisted Beltrame
Cleansed a curse for the first time
Put yourself out in water
Met Black Rabbit
Crafted a new relic
Discovered a secret room
Rescued Dodson
Defeated the Rockpile Mimic
Rescued Wayland
Enter the Halls of Din before defeating Mortar
Completely expand the Pilfer shop
Fully upgrade the pickaxe
Fully upgrade the tunic
Fully upgrade the gloves
Fully upgrade the goldsack
Fully upgrade the bombs
Die 50 times
Die 100 times
Thwart 500 pilfers
Hold 99 keys at once
Hold 99 bombs at once
Peep 100 skeletons
Discover the Golden Idol
Die with an Elixir in your inventory
Spawn a secret shop, in a secret shop, in a secret shop
Transmute 3 Relics at the same time using Transmutagen
Hold 3 of the same potion at the same time
Buy every item in a fully expanded shop
Complete a run with at least 2 hexes
Defeat Selt, Queen of Sand while Rogue's Ultimatum is applied
Defeat Noori, Spectre of Darkness while Rogue's Ultimatum is applied
Defeat Mortar, Charged Golem while Rogue's Ultimatum is applied
Defeat Selt, Mortar, Noori, Ponzu, and Seer with the same peasant
Find the Pilfer's Gift
Hatch 5 new eggs
Complete the tutorial
Defeat Ponzu, Scaled Assembly while Rogue's Ultimatum is applied
Lift the Summoning Stone 10 times
Lift the Summoning Stone 30 times
Complete a run of the Othermine
Complete 3 runs of Othermine without dying
Transform Siegfried's Aegis
Complete an Othermine run without upgrades from the antechamber chest or shops
Discover the legendary Masamune
Pay off your loans
Defeat Seer, World's Heart while Rogue's Ultimatum is applied
Defeate Din, the Old King