Here is the full list of all 48 Shadwen achievements. It takes around 12-15 hours to unlock all of the achievements on Windows.
Kill all the guards in Level 5: The Walls of Rivendon
Kill all the guards in Level 4: The Cliffside Fort
Kill all the guards in Level 3: The Way to Rivendon
Kill all the guards in Level 2: The Solitary Killer
Complete the game by leaving some or all of the guards alive, but killing the King
Complete Level 15: Inside the Castle
Complete Level 14: The Castle District
Complete Level 13: Rivendon Uptown
Kill all the guards in Level 13: Rivendon Uptown
Complete Level 12: The Streets of Rivendon
Kill all the guards in Level 12: The Streets of Rivendon
Complete Level 11: Rivendon Harbour
Kill all the guards in Level 11: Rivendon Harbour
Complete Level 10: Lowerton Worksite
Kill all the guards in Level 10: Lowerton Worksite
Complete Level 9: Lowerton Storages
Kill all the guards in Level 9: Lowerton Storages
Complete Level 8: The Roads of Lowerton
Kill all the guards in Level 8: The Roads of Lowerton
Complete Level 7: Shortwall Barracks
Complete Level 6: Longwall Prison
Complete Level 5: The Walls of Rivendon
Complete Level 4: The Cliffside Fort
Complete Level 3: The Way to Rivendon
Complete Level 2: The Solitary Killer
Don't kill anyone in Level 2: The Solitary Killer
Complete Level 1: The Apple Tree
Kill all the guards in Level 6: Longwall Prison
Kill all the guards in Level 7: Shortwall Barracks
Kill all the guards in Level 14: The Castle District
Kill all the guards in in Level 15: Rivendon Castle
Don't kill anyone in Level 3: The Way to Rivendon
Don't kill anyone in Level 4: The Cliffside Fort
Don't kill anyone in Level 5: The Walls of Rivendon
Don't kill anyone in Level 6: Longwall Prison
Don't kill anyone in Level 7: Shortwall Barracks
Don't kill anyone in Level 8: The Roads of Lowerton
Don't kill anyone in Level 9: Lowerton Storage
Don't kill anyone in Level 10: Lowerton Worksite
Don't kill anyone in Level 11: Rivendon Harbour
Don't kill anyone in Level 12: The Streets of Rivendon
Don't kill anyone in Level 13: Rivendon Uptown
Don't kill anyone in Level 14: The Castle District
Don't kill anyone in in Level 15: Rivendon Castle
Earn all the Achievements in Shadwen
Complete the game sparing the King's life after Lily discovers you're a killer
Complete the whole game killing all the guards and the King
Complete the whole game without letting Lily know you're a killer