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.
Entered the Halls of Din before defeating Mortar
Entered the Delvemore Dungeon before defeating Selt
Bought every item in a fully expanded shop
Discovered the Othermine
Fully upgraded the bombs
Completely expanded the Pilfer shop
Lifted the Summoning Stone for the first time
Defeated Seer, World's Heart
Held 99 keys at once
Held 99 bombs at once
Spawned a secret shop, in a secret shop, in a secret shop
Fully expanded the potion slots
Fully upgraded the tunic
Held 3 of the same potion at the same time
Rescued Kurtz
Fully upgraded the pickaxe
Defeated Ponzu, Scaled Assembly
Crafted 10 new relics
Fully upgraded the gloves
Stole an item from the shop
Transmuted 3 Relics at the same time using Transmutagen
Died with an Elixir in your inventory
Crafted a new potion
Hatched a new egg
Discovered Griswold, the Collector
Discovered the Golden Idol
Entered the Golden Core
Entered the Golden Core before defeating Ponzu
Thwarted 500 pilfers
Peeped 100 skeletons
Learned a new blessing
Spent 100,000 gold at shops
Rescued Lillyth
Defeated Noori, Spectre of Darkness
Fully upgraded the counter weight
Expanded the potion slot once
Healed 1,000 hp using food in one run
Entered the Shimmering Caverns
Entered the Shimmering Caverns before defeating Noori
Spent 50,000 gold at shops
Fully upgraded the goldsack
Died 50 times
Found all 3 dogs in the UnderMine
Lost 5,000 gold to pilfers
Defeated the Dungeon Gargoyles
Cleansed a curse for the first time
Spent 10,000 gold at shops
Completely expanded Dibble's shop
Defeated a Hoarding Pilfer
Entered the Halls of Din
Defeated Mortar, Charged Golem
Raised a familiar to maximum level
Found the Pilfer's Gift
Rescued Dibble
Had something popcorn 5 times in a row
Entered the Delvemore Dungeon
Defeated Selt, Queen of Sand
Assisted Beltrame
Had 6 curses active at the same time
Ate cooked food for the first time
Joined the Pilfer Loyalty Program
Completed the tutorial
Peeped 10 skeletons
Destroyed 20 signs
Died 10 times
Discovered a secret floor
Put yourself out in water
Made a deal with the demon Sho'guul
Crafted a new relic
Met Black Rabbit
Rescued Dodson
Defeated the Rockpile Mimic
Discovered a secret room
Rescued Wayland
Craft 20 new relics
Craft 10 new potions
Learn 10 new blessings
Die 100 times
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
Hatch 5 new eggs
Craft 30 new relics
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