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