Here is the full list of all 30 The Dark Pictures Anthology: Man of Medan achievements.
Finished the Shared Story
Chose all of the Heart decisions
Only the men survived!
Chose all of the Head decisions
Finished Movie Night
Maxed Conrad and Fliss's Relationship
Maxed Brad and Alex's Relationship
Only the women survived!
Unlocked Fliss's Arrogant Trait
Found all of the black framed Pictures
Found all Pictures
Found all Secrets!
Unlocked Julia's Spoilt Trait
No-one survived!
Calmed Junior down
Conrad successfully escaped on the speedboat
Opened the window without making noise
Everybody survived!
Completed the Solo Story
Found all of the white framed Pictures
Revealed the name of the ship
Found 25 Secrets!
Maxed Alex and Julia's Relationship
Completed 10 QTEs in succession
Unlocked Alex's Aggressive Trait
Unlocked Conrad's Humorous Trait
Julia accepted Alex's proposal
Conrad successfully flirted with Fliss
Unlocked Brad's Envious Trait
Beat the Training Dummy