Here is the full list of all 30 The Dark Pictures Anthology: Man of Medan achievements worth 1,000 gamerscore.
Julia accepted Alex's proposal
Conrad successfully flirted with Fliss
Unlocked Brad's Envious Trait
Find 25 Secrets
Find all of the Secrets
Finish the Shared Story
Finish Movie Night
Beat the Training Dummy
Complete 10 QTEs in succession
Open the window without making noise
Unlock Alex's Aggressive Trait
Unlock Fliss's Arrogant Trait
Unlock Julia's Spoilt Trait
Unlock Conrad's Humorous Trait
Choose all of the Heart decisions
Choose all of the Head decisions
Escape on the speedboat
Reveal the name of the ship
Calm Junior down
Find all of the black Framed Pictures
Find all of the white Framed Pictures
Finish the Solo Story
Save only the women
Save only the men
Maximise Alex and Julia's relationship
Maximise Conrad and Fliss's relationship
Maximise Brad and Alex's relationship
Find all of the Pictures
Kill all Characters
Save everyone