Full list of all 70 Borderlands (JP) achievements worth 1,500 gamerscore. It takes around 20-25 hours to unlock all of the achievements in the base game.
The base game contains 50 achievements worth 1,000 Gamerscore, and there are 3 DLC packs containing 20 achievements worth 500 Gamerscore.
Earned level 50
Earned level 40
Killed the Vault Boss
Discovered Eridian Promontory
Completed all missions in the Rust Commons
Discovered Crimson Lance Enclave
Rescued enough Claptraps to earn 42 inventory slots
Killed Flynt
Killed the Rakk Hive
Discovered Trash Coast
Killed Krom
I bet you never thought you'd be here.
Discovered The Scrapyard
Completed 5 missions in the Rust Commons
Raced around the Ludicrous Speedway in record time
Completed all missions in the Arid Badlands
Mastered the technology of Pandora
Killed 25 enemies with corrosive weapons
Applied an elemental artifact
Emerged victorious from an arena match
Killed 25 enemies with explosive weapons
Killed Sledge
Defeated the Rakk Hive, the Vault Boss, Sledge, Krom, or Flynt in a co-op game
Discovered Headstone Mine
Discovered Sledge's Safe House
Killed 5 Rakk in under 10 seconds
Killed 25 enemies by ramming them with any vehicle
Kill 25 enemies with shock weapons
Complete 15 missions in co-op
Rescue a groupmate from death in a co-op game
Won a duel against another player
Won a duel without taking damage
Equipped a class mod for your character
Discovered Krom's Canyon
Earned level 30
Sold 50 guns to a shop
Earned level 20
Reached proficiency level 10 with any weapon type
Earned level 10
Earned $1,000,000
Killed 25 enemies with incendiary weapons
Killed 15 enemies with the Hunter's action skill
Killed 15 enemies with the Soldier's action skill
Killed an enemy plumber-style
Killed 15 enemies with the Berserker's action skill
Discovered Skag Gully
Kill an enemy with the Siren's action skill
Earned level 5
Play in a co-op game with either an employee of Gearbox or someone who has this achievement
Completed 5 missions in the Arid Badlands
Complete the "Braaaaaaaaaaaaains!" mission
Killed Ned. Again.
Killed Ned...sort of
Complete the "Jakobs Fodder" mission
Complete the "House of the Ned" mission
Reach the end of the larger challenge in the Hell-Burbia coliseum
Reach the end of each of the 3 larger challenges with one character
Reach the end of the larger challenge in The Angelic Ruins coliseum
Reach the end of the larger challenge in The Gully coliseum
Complete the Prove Yourself mission
Complete all missions in Secret Armory
Kill each of the loot midgets
Reach Level 61
Destroy the Lance Depot
Rescue Athena
Paid for a worthless tour of the world's largest bullet
Destroy a Lancer while in a Racer
Build the New Car: Monster
Reach Level 51
Kill Crawmerax the Invincible