Here is the full list of all 28 Vampyr achievements. It takes around 35-40 hours to unlock all of the achievements on Windows.
Embrace Clay during your first meeting with him
Complete the game
Finish the game without killing any citizens
Defeat The Disaster
Save this poor plant with water
Turn a district to hostile status
Turn all districts to hostile status
Find all ranged weapons
Find all melee weapons
Find all off-hand weapons
Find the recollection of Paulus Aurelianus
Gather all collectibles
Take care of Swansea's fate
Defeat McCullum
Take care of Aloysius's fate
Upgrade a weapon to level 5
Defeat Doris
Defeat Mary
Take care of Sean's fate
Defeat Fergal
Heal 10 citizens
Upgrade a weapon with a module
Take care of Dorothy's fate
Eat 10 rats
Let Clay live during your first meeting with him
Take a ride with Doctor Swansea
Upgrade a weapon
Go to the Shelter and rest …