Here is the full list of all 41 SCP: Containment Breach Multiplayer achievements.
Encountered the Hole In The Wall.
Encountered the Sleep Entities.
Encountered an Old Coffin.
Encountered the Shy Guy.
Encountered the Possessive Mask.
Encountered the Shadow Lamps.
Acquired the S-NAV Navigator Ultimate.
Encountered the Zombie Plague.
Found a Blue Key.
Encountered the Clockworks Machine.
Found the cure.
Encountered the Bad Composition.
Encountered the Peripheral Jumper.
Escaped the Old Man's Pocket Dimension.
Lured the Old Man through a Tesla gate.
Encountered the Old Man.
Encountered the Creatures with Many Voices.
Encountered the Builder Bear.
Encountered a Recursive Room.
First played the multiplayer.
Recontained SCP-055.
Encountered the Old AI.
Acquired the "Telekill Alloy".
Obtained a liquid from the Coffee Machine.
Used SCP-420.
Found and equipped the "Lovecraftian Locket".
Swallowed a sample of Panacea.
Encountered an Old Cowbell.
Found a Jaded Ring.
Encountered the Ghost.
Read the Encyclopedia of Common Diseases.
Encountered the Atrocity Skull.
Entered Doctor Maynard's office.
Entered Doctor Harp's office.
Acquired an Omni-level Keycard.
Didn't use console commands.
Wore a GP-5 Gas Mask.
Beat the game on Keter difficulty.
Escaped the facility in breach mode.
Became MTF in breach mode.
Became scientist in breach mode.