Here is the full list of all 57 GTFO achievements.
Find 20 story logs in the Complex
Kill a total of 20 enemies with one tripmine
Start the nuclear meltdown in R8
Complete all Sectors in R7
Complete all Main Sectors in R7
Kill a Mother without it having used its spawning ability
Kill a P-mother without taking any damage from baby strikers
Achieve Prisoner Efficiency by completing the Main, Overload and Secondary Sectors of an expedition in one attempt
Complete an expedition with four player without anyone getting downed
Complete any C-tier expedition without anyone using the active ability of their tools
Complete any E-tier expedition without using any boosters
Complete an expedition with at least one Booster activated
Fail an expedition for the first time
Find 5 story logs in the Complex
Survive a class V or higher alarm without anyone taking any damage
Kill a Scout with a melee attack without it detecting you
Kill a Tank without anyone on the team taking any damage
Teleport to another dimension for the first time
Complete a Main Sector
Complete a Secondary Sector
Complete an Overload Sector
Complete all Main Sectors in ALT://R1
Complete all Main Sectors in ALT://R3
Complete an expedition without getting downed
Complete the Tutorial
Complete all Main Sectors in ALT://R2
Complete all Main Sectors in ALT://R4
Complete all Main Sectors in ALT://R5
Complete all Main Sectors in ALT://R6
Complete all Main Sectors in R8
Complete all Secondary Sectors in all Rundowns
Complete all Overload Sectors in all Rundowns
Complete all Sectors in all Rundowns
Complete any A-tier expedition not killing any enemies with main or secondary weapons
Complete any B-tier expedition alone with only pistols or revolvers equipped as main and secondary
Complete any D-tier expedition with everyone using shotguns equipped as main and secondary
Kill a Giant by yourself using only melee weapons
Kill a Snatcher that has captured a teammate
Complete any D-tier expedition without any doors being broken
Complete any B-tier expedition without anyone having turned on the flashlight
Descend a total of 100 kilometers into the complex with the elevator
Find 50 story logs in the Complex
Find every story log in the Complex
Find Schaeffer's bucket
Complete all Sectors in ALT://R4
Complete all Sectors in ALT://R5
Complete all Sectors in ALT://R6
Complete all Sectors in R8
Complete all Main Sectors
Complete R8D1 without using any health kits or disinfectants
Complete any expedition having marked every enemy on the map using the Biotracker
Achieve Prisoner Efficiency in all expeditions that have Secondary and Overload Sectors
Hear a Voice of Truth broadcast for the first time
Find all character backstory logs in ALT://R5
Don't start the nuclear meltdown in R8
Come face to face with Schaeffer
Discover Schaeffer's secret message