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