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.
Collected 15 Claptrap bobbleheads
Completed each of the larger challenges in all 3 coliseums
Completed the larger challenge in The Gully coliseum
Completed the larger challenge in The Angelic Ruins coliseum
Completed the larger challenge in the Hell-Burbia coliseum
Found 25 oil cans
Collected 3 panties, 5 fish in a bag, and 15 pizzas
Killed an enemy with the Siren's action skill
Killed 15 enemies with the Hunter's action skill
Killed 15 enemies with the Soldier's action skill
Killed an enemy plumber-style
Completed the lesser challenge in all 3 coliseums
Completed all missions in Secret Armory
Killed Crawmerax the Invincible
Found all 6 Claptrap statues
Completed a crazy request for Tannis
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
Destroyed Lance Depot
Paid for a worthless tour of the world's largest bullet
Rescued Athena
Destroyed a Lancer while in a Racer
Built the New Car: Monster
Completed the "Braaaaaaaaaaaaains!" mission
Reached Level 61
Killed Ned. Again.
Killed Ned...sort of
Completed the "Jakobs Fodder" mission
Completed the "House of the Ned" mission
I bet you never thought you'd be here
Reached Level 51
Earned level 50
Completed 15 missions in co-op
Earned level 40
Defeated the Rakk Hive, the Vault Boss, Sledge, Krom, or Flynt in a co-op game
Rescued a groupmate from death in a co-op game
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.
Killed the Vault Boss
Discovered Eridian Promontory
Discovered Crimson Lance Enclave
Completed all missions in the Rust Commons
Killed Flynt
Rescued enough Claptraps to earn 42 inventory slots
Killed the Rakk Hive
Discovered Trash Coast
Earned level 30
Earned $1,000,000
Killed Krom
Discovered Krom's Canyon
Killed 25 enemies with shock weapons
Killed 25 enemies with corrosive weapons
Discovered The Scrapyard
Completed 5 missions in the Rust Commons
Reached proficiency level 10 with any weapon type
Raced around the Ludicrous Speedway in record time
Completed all missions in the Arid Badlands
Earned level 20
Killed Sledge
Equipped a class mod for your character
Discovered Headstone Mine
Killed 25 enemies with explosive weapons
Killed 15 enemies with the Berserker's action skill
Sold 50 guns to a shop
Applied an elemental artifact
Discovered Sledge's Safe House
Mastered the technology of Pandora
Killed 25 enemies by ramming them with any vehicle
Killed 5 Rakk in under 10 seconds
Earned level 10
Killed 25 enemies with incendiary weapons
Discovered Skag Gully
Earned level 5
Completed 5 missions in the Arid Badlands