Here is the full list of all 23 The Innsmouth Case achievements.
Played through all endings
Discovered all of Innsmouth
Mentioned your vegan lifestyle 3 times
Snooped through an abandoned hotel room
Played a creepy Arcade Game
Wendy found a safe place
Saved from the stake
Pissed Dahlia off to death
Used dirty methods to avoid payment
Overpowered the gawper
Snooped through the Marsh Family records
Found a couple of weird City Hall records
Didn’t touch the cube in the lighthouse
Discovered fragments from Innsmouth’s history
Traumatized Evelyn
Dahlia spared your life
Seduced Ethel
Spent a night with Dahlia
Slept with Priscilla
Became friends with Jonah
Survived a night in the Gilman Hotel
Wrongdoings have consequences
Slept with a fish creature