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