Full list of all 80 Borderlands Game of the Year Enhanced achievements. It takes around 60-80 hours to unlock all of the achievements on Windows.
Completed the larger challenge in The Angelic Ruins coliseum
Completed each of the larger challenges in all 3 coliseums
Killed 15 enemies with the Berserker's action skill
Killed 15 enemies with the Hunter's action skill
Completed the larger challenge in the Hell-Burbia coliseum
Killed 15 enemies with the Soldier's action skill
Completed all missions in Secret Armory
Killed Crawmerax the Invincible
Collected 15 Claptrap bobbleheads
Completed the larger challenge in The Gully coliseum
Collected 3 panties, 5 fish in a bag, and 15 pizzas
Found 25 oil cans
Reached Level 61
Reached Level 51
Earned level 50
Emerged victorious from an arena match
Won a duel against another player
Won a duel without taking damage
Play with at least two other players.
Completed a crazy request for Tannis
Found all 6 Claptrap statues
Collected 5 3D glasses
Killed the Interplanetary Ninja Assassin Claptrap
Killed Commandant Steele-trap
Killed Dr. Ned-trap
Killed General Knoxx-trap
Killed each of the loot midgets
Paid for a worthless tour of the world's largest bullet
Destroyed Lance Depot
Destroyed a Lancer while in a Racer
Rescued Athena
Completed 15 missions in co-op
Built the New Car: Monster
Completed the lesser challenge in all 3 coliseums
Completed the "Braaaaaaaaaaaaains!" mission
Killed Ned. Again.
Killed Ned...sort of
Earned level 40
Completed the "Jakobs Fodder" mission
Completed the "House of the Ned" mission
Rescued enough Claptraps to earn 42 inventory slots
I bet you never thought you'd be here
Raced around the Ludicrous Speedway in record time
Killed the Vault Boss
Discovered Eridian Promontory
Discovered Crimson Lance Enclave
Completed all missions in the Rust Commons
Killed Flynt
Killed the Rakk Hive
Discovered Trash Coast
Earned level 30
Earned $1,000,000
Killed Krom
Discovered Krom's Canyon
Defeated the Rakk Hive, the Vault Boss, Sledge, Krom, or Flynt in a co-op game
Discovered The Scrapyard
Rescued a groupmate from death in a co-op game
Completed 5 missions in the Rust Commons
Reached proficiency level 10 with any weapon type
Completed all missions in the Arid Badlands
Earned level 20
Killed 25 enemies with corrosive weapons
Applied an elemental artifact
Equipped a class mod for your character
Killed Sledge
Killed 25 enemies with shock weapons
Discovered Headstone Mine
Mastered the technology of Pandora
Sold 50 guns to a shop
Discovered Sledge's Safe House
Killed 25 enemies by ramming them with any vehicle
Earned level 10
Killed 5 Rakk in under 10 seconds
Killed 25 enemies with incendiary weapons
Discovered Skag Gully
Killed an enemy with the Siren's action skill
Earned level 5
Killed an enemy plumber-style
Killed 25 enemies with explosive weapons
Completed 5 missions in the Arid Badlands