Here is the full list of all 10 Eternal Threads achievements.
Read all letters in the house.
Listen to voicemails for all six housemates.
Receive a final revelation.
Save all six housemates while also resolving their personal issues.
Watch all possible death scenes across all the possible time lines.
Watch all the housemates reveal their secrets.
Save all six housemates.
Open all four locked doors in the house.
Save one housemate.
Witness every possible event across all the different timelines.