Here is the full list of all 104 I Shall Remain achievements.
Finish the story on Easy difficulty
Finish the game with "Civilian" perk
Kill Halfing Aberration
Kill De Rossi
Kill Bunny
Kill Kramer
Kill Mantis Aberration
Kill Hetzenauer
Kill 5000 infected
Kill Geronimo
Kill Guardian
Kill Big Brother
Throw 100 grenades
Unlock Tommy's second ability
Kill Monk
Kill Child
Unlock Thomas's second ability
Reach level 30 with main character
Kill Martha
Kill Freddy
Kill Renan
Recruit C.J.
Kill Krass
Unlock Jim's second ability
Kill Hunterlag
Use mechanical actions 50 times
Kill 500 elite infected
Read 30 books
Recruit Thomas
Unlock Cathy's second ability
Kill Vilebyrd
Plant 50 mines
Use medical actions 100 times
Kill Newborn
Reach level 20 with main character
Recruit Jim
Kill Wilson
Kill Reaper
Kill Realdead Man
Recruit Andrea
Kill Infant
Recruit Tommy
Throw 50 grenades
Kill Strider
Kill Lisard
Kill Linger
Read 20 books
Unlock Patrick's second ability
Use mechanical actions 10 times
Use medical actions 50 times
Kill Carrie
Recruit Cathy
Meet Julia
Kill 100 elite infected
Kill Ghunter
Read 10 books
Kill 1000 infected
Kill 50 elite infected
Recruit Patrick
Reach level 10 with main character
Repair the tank
Kill Murthog
Kill 500 infected
Plant 10 mines
Throw 10 grenades
Meet Dr. Andre Gratia
Kill Coloth
Kill 10 elite infected
Kill Beizel
Kill 200 infected
Finish Prologue
Use medical actions 10 times
Find Michael, your brother
Kill Gobber
Kill 100 infected
Read one book
Kill one Infected
Reach level 40 with main character
Use medical actions 500 times
Use mechanical actions 100 times
Use mechanical actions 500 times
Throw 500 grenades
Plant 100 mines
Plant 500 mines
Unlock Andrea's second ability
Unlock C.J.'s second ability
Finish the story on Normal difficulty
Finish the story on Hard difficulty
Finish the story on Impossible difficulty
Finish the story on Easy difficulty (Hardcore)
Finish the story on Normal difficulty (Hardcore)
Finish the story on Hard difficulty (Hardcore)
Finish the story on Impossible difficulty (Hardcore)
Finish the game without using any unique weapon
Finish the game with "Athlete" perk
Finish the game with "Fighter" perk
Finish the game with "Detective" perk
Finish the game with "Policeman" perk
Finish the game with "Trooper" perk
Finish the game with "Agent" perk
Finish the game with "Sapper" perk
Finish the game with "Chieftain" perk
Finish the game with "Survivalist" perk
Kill Crawler Aberration