Here is the full list of all 17 Backrooms Break achievements.
Theseus would be proud
We need to go deeper
Kill the invisible monster
..or is it?
Found the elevator
Acquired the assault rifle
Found first weapon attachment
Acquired first gun
Found the gun cabinet key
Hopefully it's almond water
How do I get out of this place?
Died for the first time
Get a first kill
Escorted the ball into the elevator
Acquired the shotgun
Acquired the sniper rifle
Break all the walls in Level 0