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