Here is the full list of all 31 ColdSide achievements.
Get one of the alternate endings
You don't remember anything
Complete Level 5
Find all figurines in level 5
Finish Level 4
Read all notes on the fourth level
Don't pet the cat
You took a dip in an anomalous pool
Complete 3rd level
Read all notes on the third level
Complete second level
Read all notes on the second level
Complete first level
Read all notes on the first level
What's going on with you?
You're at the place
Start playing ColdSide
Find all the figurines on the first level
Find all the figurines on the second level
Find all the figurines on the third level
Find all the figurines on the fourth level
Collect all figurines on the sixth level
Finish Level 6
Get True Ending
Join the rebels
You've been torn to shreds.
Strange anomaly
Finishing the game without dying
Open a closed door
Find the monster figurine
You have taken a card from a Foundation soldier without violence