Here is the full list of all 20 Saturnalia achievements.
Run out of stamina 5 times
Complete Anita's Mission
Light up all the bonfires in Gravoi
Light all the votive candles in the church
Complete Claudia's Mission
Replenish your stamina 3 times while the Creature is chasing you
Distract the Creature 5 times using the firecrackers
Flash the Creature 5 times
Team up with another character 3 times to reach a destination
Turn on all the lights inside the Mines
Use 100 matches
Collect 3 tips from the Mouth of Truth
Complete Paul's Mission
Get captured while using a phone
Use a phone 5 times to gather your companions
Read at least 90 clues
Rescue a captured character 6 times
Complete Sergio's Mission
Complete Tecla's Act
Find all the tools and consumables