Full list of all 50 Legendary achievements worth 1,000 gamerscore. It takes around 60-80 hours to unlock all of the achievements on Xbox 360.
Survived a ranked 4v4 Multiplayer game without being killed
Started and finished a ranked Multiplayer match
Bypass the electronic lock in Episode 1
Chop your way out of the Internet Café with the Fire Axe in Episode 1
Create a ramp with the soda machine using your pistol in Episode 1
Extinguish the doorway fire using the water valve in Episode 1
Complete Episode 1 on any difficulty
Unlock the warehouse exit in Episode 2
Find the Black Order-eliminating electric switch in Episode 2
Complete Episode 2 on any difficulty
Get stepped on by the Giant Golem in Episode 3
Escape the Nari-possessed vending machine room in Episode 3
Look at all "The Great Langtini" posters littering Times Square in Episode 3
Destroy the Giant Golem in Episode 3
Complete Episode 3 on any difficulty
Destroy a Blood Spider Queen in Episode 4
Defeat the first Alpha Werewolf in Episode 4
Eavesdrop on the Black Order as they cage up a Werewolf in Episode 4
Complete Episode 4 on any difficulty
Defeat the Minotaur in Episode 5
Entice the Minotaur to destroy all Graveyard wall sections in Episode 5
Defeat the Griffon in Episode 5
Complete Episode 5 on any difficulty
Run all Council Base lab experiments in Episode 6
Shoot down the low flying Griffons in Episode 6
Complete Episode 6 on any difficulty
Cause the crane to drop the metal beams in Episode 7
Take out the power to the Black Order outpost in Episode 7
Complete Episode 7 on any difficulty
Survive the double Minotaur attack in Episode 8
The Lead Designer apologizes for writing the terrible pun "DouBull TrouBull" - have some points
Free Vivian from captivity in Episode 8
Complete Episode 8 on any difficulty
Complete game on Easy difficulty
Complete game on Normal difficulty
Complete game on Hard difficulty
Collect 1/2 of PDA pick-ups
Collect all PDA pick-ups
Fire all 8 projectile weapons in Single Player at least once
Kill 25 enemies with the Fire Axe in Single Player
Use the Animus Pulse ability 10 times
Use Animus to change the frequency of an Aniform Control Device in Single Player
Fire every weapon available in any ranked Multiplayer match
Fill 50% of your team's Monster Machine with Animus in a ranked 4v4 Multiplayer match
Kill 10 Werewolves in a ranked Multiplayer match without being killed
Kill 10 enemy players in a ranked Multiplayer match without being killed
Ranked 4x4, max Animus match: fill 25% of machine, kill 10 players, 10 werewolves, win the match
Be first place in kills in 10 ranked Multiplayer matches in a row
Play 200 ranked Multiplayer matches
Win 50 ranked Multiplayer matches