Here is the full list of all 18 Hollowed achievements.
Saving Inna
Choosing Oco
Surviving the Collapse
Meeting the god
Roaming the gods realm
Sinking deep
Running from the past
Scaling the world
Making a trade
Seeing the future
Expressing aggression
Rejecting Life
Moving forward decisively
Learning the motivation
Creating a relationship
A life after death
Ringing the Bells
Avoiding the seeking hands