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