Here is the full list of all 17 Stray Souls achievements.
Complete the Grandma’s House level
Complete the Forest level
Complete the Graveyard level
Complete the Police Station level
Complete the Aspen Falls Level
Complete the Nowhere level
Get the “Hero” ending
Get the “Apathy” ending
Get the “Revenge” ending
Read all in-game documents
Pet Klopsik
Defeat all enemies in “Aspen Falls” level
Shoot down all the Cult symbols in the Forest level
Beat the game without taking damage
Beat the game in under 2.5 hrs
Unlock all of Martha’s secret cutscenes
Unlock all trophies