Here is the full list of all 119 Torchlight II achievements. It takes around 200 hours to unlock all of the achievements on Windows.
Defeat Verona
Defeat Aleera
Defeat Marishka
Defeat Cacklespit
Defeat Vyrax
Explode 10,000 enemies
Reach level 100
Wear a completed armor set
Socket 50 gems into items
Find a legendary item
Add a friend
Do 10,000 damage with a single attack
Open 500 chests
Deal 10,000 critical strikes
Break 1,000 breakables
Defeat the Winter Widow
Begin new game plus
Obtain a tier 2 skill bonus
Use a map
Defeat the Nether King as a Berserker
Defeat the Nether King in Casual difficulty
Defeat the Nether King in Normal difficulty
Defeat the Nether King
Defeat the Dark Alchemist
Use 500 potions
Defeat Killbot
Defeat Thiss
Take 50,000 steps
Defeat Bloatfang
Defeat the Grizzled Alpha
Fish using dynamite
Defeat the Siege Guardian
Teach a pet 4 spells
Defeat Ezrek Khan
Defeat Aruk
Use an enchanter 50 times
Defeat 100 champions
Defeat the Artificer
Squish 100 critters
Learn 4 spells
Destroy a socketed gem
Purchase 100 items from the gambler
Have 1,000,000 gold
Purchase 50 items from the gambler
Purchase 20 items from the gambler
Use an enchanter 10 times
Have 100,000 gold
Defeat the Manticore's Mate
Defeat the Manticore
Teach a pet a spell
Deal 1,000 critical strikes
Sell 500 items
Recover a gem from an item
Socket a gem into an item
Learn a spell
Trade an item with another player
Join a multiplayer game
Start a multiplayer game
Defeat Grand Regent Eldrayn
Use 50 potions
Defeat King Pogg
Defeat Chillhoof
Defeat Kidrik the Mauler
Take 10,000 steps
Explode 1,000 enemies
Open 100 chests
Defeat General Grell
Find a secret room
Break 100 breakables
Defeat 25 champions
Defeat One-Eyed Willy
Defeat Mordrox
Obtain a tier 1 skill bonus
Fish 10 times
Send your pet to town
Defeat the Fallen Guardian
Open 20 chests
Explode 100 enemies
Defeat the Nether King with each of the 4 classes
Defeat the Nether King in Elite difficulty
Defeat the Nether King in Veteran difficulty
Defeat the Nether King as an Embermage
Defeat the Nether King as an Engineer
Defeat the Nether King in hardcore mode (casual)
Defeat the Nether King in hardcore mode (elite)
Defeat the Nether King in hardcore mode (normal)
Defeat the Nether King in hardcore mode (veteran)
Defeat the Nether King as an Outlander
Defeat the Wraith Lord
Break 10,000 breakables
Deal 100,000 critical strikes
Use an enchanter 500 times
Fish 100 times
Fish 1,000 times
Have 10 friends
Have 50 friends
Die with a hardcore character
Start a hardcore character
Have 10,000,000 gold
Defeat 500 champions
Take 100,000 steps
Recover 10 gems from items
Recover 100 gems from items
Destroy 10 socketed gems
Destroy 100 socketed gems
Find 10 secret rooms
Find 100 secret rooms
Sell 5,000 items
Sell 50,000 items
Obtain a tier 3 skill bonus
Socket 500 gems into items
Use 10 maps
Use 100 maps
Use 5,000 potions
Assemble TrillBot
Defeat the King In Masks
Defeat Boletus Rex
Squish 500 critters
Squish 1000 critters