Here is the full list of all 51 Gabriel Knight: Sins of the Fathers 20th Anniversary Edition achievements.
Complete with game with a full score of 362 points
Don't try to save Malia
Enter the ceremony alone
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
Exhaust Dr. John on the topic of Voodoo
Compliment Gran as thoroughly as she deserves
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
Read Gunter's journal
Complete Day 6
Leave your own Voodoo code message
Hide the tracker
Get inside Mosely's Office
Decode the rada drum message
Complete Day 5
Change Mosely's mind about the Voodoo Murders Case
Survive the deadly python
Take in a snake dance performance
Translate a mysterious code
Complete Day 4
Witness a chilling death
Help Sam improve his game
Make a large purchase from Willy
Find the secrets of Granddaddy's Clock
Complete Day 3
Have a fated run-in
Have your fortune told
Make a jewelry mold
Find Madame Cazaunoux's address
Sit through the Voodoo lecture
Complete Day 2
Get a copy of the Voodoo Murders File
Excessive flirting!
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