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