Here is the full list of all 30 The Dark Pictures Anthology: Little Hope achievements worth 1,000 gamerscore.
Saved Andrew
Understanding was one of top two traits for Angela
Saved Angela
Completed 5 combat events in succession
Amiable was one of top two traits for Daniel
Maximized Daniel and Taylor's Relationship
Headstrong was one of top two traits for Taylor
Completed the prologue
Find all witchcraft secrets
Finish Movie Night
Defeat Taylor's demons
Mary must be saved
Unlock John's Rational Trait
Unlock Andrew's Compassionate Trait
Choose all of the Heart decisions
Choose all of the Head decisions
Daniel must survive
Taylor must survive
John must survive
Find all of the black Framed Pictures
Find all of the white Framed Pictures
Finish the Solo Story
Everyone must die at the ruined house
Everyone must survive
Maximize Angela and John's relationship
Andrew must have a good relationship with all characters
Find all family secrets
Find all of the Pictures
Kill all Characters
Andrew must be the sole survivor with a weapon