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