Here is the full list of all 51 Gabriel Knight: Sins of the Fathers 20th Anniversary Edition achievements.
Don't try to save Malia
Complete the game with less than 362 points
Complete Day 10
Try to save Malia
Enter the ceremony with back-up
Enter the secret Voodoo Hounfour
Complete Day 9
Get past the mummies like a true adventurer!
Collect all the tiles
Complete Day 8
Complete your research
Open a secret door
Complete day 7
Complete the intiation ceremony
Discover a shocking loss
Have a long chat with Wolfgang
Complete Day 6
Decode the rada drum message
Leave your own Voodoo code message
Hide the tracker
Get inside Mosely's Office
Complete Day 5
Translate a mysterious code
Take in a snake dance performance
Change Mosely's mind about the Voodoo Murders Case
Survive the deadly python
Read Gunter's journal
Complete Day 4
Find the secrets of Granddaddy's Clock
Witness a chilling death
Help Sam improve his game
Make a large purchase from Willy
Compliment Gran as thoroughly as she deserves
Complete Day 3
Make a jewelry mold
Have a fated run-in
Have your fortune told
Sit through the Voodoo lecture
Find Madame Cazaunoux's address
Complete Day 2
Excessive flirting!
Get a copy of the Voodoo Murders File
Exhaust Dr. John on the topic of Voodoo
Obtain a false ID
Complete Day 1
Find a clue at Lake Pontchartrain
Meet Malia Gedde
Get rid of the cop in Jackson Square
Read the Paper on Day 1
Enter the ceremony alone
Complete with game with a full score of 362 points