Here is the full list of all 19 Synthetic Lover achievements.
Romance Bastian
Fly on a hoverbike
Watch your companion impress a lady
Make sure Bastian’s doesn’t suffer at the hands of the thugs
Conceal Bastian’s real name
Play through the entire common route of the game
Avoid making Bastian uncomfortable when in bed together
Experience death early in the game
Romance Bastian and Terrance, and make out with Karim
Push the limit bargaining with the Biotech but make sure Bastian survives
Get both Friendship Endings
Romance Terrance
Get Bastian and Terrance to touch your body with their bare hands in a casual way
Finish both routes without romancing or becoming close with the two main love interests
Claim that gender identity isn’t important to you
Unlock all endings in the game
Politely refuse an offering of food
Get a new biot designation number
Get all the main 18 achievements of the Synthetic Lover Game