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