Here is the full list of all 52 Gangs of Sherwood achievements.
Complete all the story acts on Normal difficulty
Complete all the story acts with all heroes
Finish every mission with more than one player
Kill all of Marian's siblings
Eliminate Guy of Gisborne
Eliminate the Prioress of Kirklees and Red Roger
Eliminate the Sheriff of Nottingham
Defeat The Ram
Kill 15 enemies by pushing or throwing them off ledges
Perform a 100 hit combo
Perform 15 Parry Attacks in total
Be in Rebel Instinct for a combined total of 2 minutes
As Robin, successfully fire a total of 100 Star Arrows
As Friar Tuck, successfully perform 100 Charge Attacks
As Little John, successfully perform 100 Heat Attacks
Perform 25 Finishers
Launch 50 different enemies
Grapple Attack 25 enemies
Complete the Tyrant's Pit in under 10 minutes
Donate Gold to a Resistance's Checkpoint
Purchase an Outfit at the Remington Cole
Complete Major Oak Calls
Perform an Air Combo
Earn an S-rank in any encounter
Raise the Gang's Power to Level 4 while in any Mission
Revive an ally
Find and equip your first Artifact
Activate Rebel Instinct
Perform a Rebel Ability
Perform a Finisher
Get a Headshot Kill on an enemy
Perform a Throw on a enemy
Defeat an enemy by lighting them on fire
Push an enemy so they fall off a ledge
Purchase the Origin Outfit at Remington Cole
Complete all the People's Requests
Unlock all Gears for all for one hero
Unlock all Gears for all for all heroes
Complete all Challenges
Complete all Lessons
Buy everything from Antonna Carridge with all Heroes
Buy everything from Antonna Carridge with one Hero
Find and equip all the different Artifacts
Find all the Gang's Mementos
Find all of Alan-a-Dale's puppets
Donate 5000 Gold at the end of any Mission
Kill all the Crows in Edwinstowe
As Robin, get killed by the Prioress of Kirklees
High five with an ally
Kill an enemy by throwing Gold at them
Finish any Mission with more than one player
As Marian, successfully perform 100 Flux triggers