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