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