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