Here is the full list of all 39 Labyrinthine achievements.
Complete your first case file
Complete Chapter 5
Complete Chapter 4
Complete Chapter 3
Complete Chapter 2
Complete Chapter 1
Revive a player for the first time.
Find all of the guide books hidden in Zone 1
Find all of the guide books hidden in Zone 2
Complete a case after being downed 5 or more times.
Have a monster chasing you kill another player instead
Find all of the medallions hidden in Chapter 5
Betray another player using the flaregun, causing them to die to a monster
Stop a charging monster with the flaregun just before it hits you
Find all of the hidden miner cards in Chapter 6
Complete Chapter 6
Find All 10 Keys on Chapter 4
Reached level 5 in case files
Reached level 10 in case files
Reached level 25 in case files
Reached level 50 in case files
Reached level 100 in case files
Find your first cosmetic
Find 25 Unique Cosmetics
Find 100 Unique Cosmetics
Complete a hardcore case file
Complete a total of 50 hardcore case files
Complete an Extreme Giant map
Spend 1,000 total tickets in the shop
Spend 10,000 total tickets in the shop
Buy every cosmetic in the shop
Wear a cosmetic in every available cosmetic slot
Complete all daily quests for the day