Here is the full list of all 17 ERSATZ achievements.
Completed the basic survival training
Unlocked the simulation "Synthesis"
Beaten Type Alpha for the first time
Beaten Type Beta for the first time
Beaten Type Gamma for the first time
Achieved your first 'S' Rank
'S' ranked every level in Type Alpha
'S' ranked every level in Type Beta
'S' ranked every level in Type Gamma
Beaten Journey Mode Alpha in Under 60 Minutes
Beaten Journey Mode Beta in under 60 Minutes
Beaten Journey Mode Gamma in under 60 Minutes
Beat any Normal Mode level without taking a single hit
Beat any Journey Mode without getting a single Game Over screen
Collect all 8 hidden decryption keys
Completed Ersatz 100%
Beaten Synth Rush ALL on any type