Here is the full list of all 39 Blacksad: Under the Skin achievements.
Do not take the case.
Stand up to Sam as many times as you can.
Find all false endings in the game.
Watch all 6 alternate scenes at the end of the game.
Contribute to as many deaths as possible.
Complete the Hockey sheet of the Hall of Fame album.
Complete the Baseball sheet of the Hall of Fame album.
Complete the Hall of Fame album.
Complete the Football sheet of the Hall of Fame album.
Complete the Boxing sheet of the Hall of Fame album.
Help the Colberts live a second honeymoon and receive their gratitude.
Get hired twice for the same case.
Buy your favorite goat a second burger.
Complete the game without dying a single time.
Complete the game dying less than 9 times.
Now for real.
Complete all deductions in the game.
Solve the case.
Take your sixth beating.
Do not scare Brunhilda while telling her a story.
Beat someone up for once.
Play baseball.
Complete Blacksad's silence conveniently.
Play good cop convincingly.
Play bad cop convincingly.
Take your fifth beating.
Interact with as many books as you can.
Why's that poster in Dunn's flat?
Put your acting skills to the test.
Stand up to Quince as many times as you can.
Charm Helen Moore into giving you a present.
Take your fourth beating.
Buy a box of cigarettes from the nursing staff.
Take your third beating.
Take a ride with the city's most honest bookmarker.
Take your second beating.
Take 400 nightstick blows. Maybe a few less.
Find your most valuable tool.
Take your first beating (spoiler: it won't be the last!).