Here is the full list of all 41 Venture to the Vile achievements.
Completed the Prologue
Completed Act 01
Investigated the Black Hill Mines
Investigated Seasalter Harbour
Completed Act 02
Completed Act 03
Upgraded the mutations to full
Found all the horseshoes
Found all the lost children
Finished all crook quests
Upgraded Tonics to full
Unlocked all the costumes
Completed In Memoriam
Kill Mr Hare
Upgrade Wall Creeper
Unlocked Beast Dash
Finished all of Elsie’s quests
Unlocked all Achievements
Complete the game with the Prisoner’s Garb equipped
Defeat the Angler
Dredge the depths of the plague pit
Defeat what lies beneath the hospital
Defeat what lurks inside the windmill
Defeat what hides in the rafters
Make Derek Mouse proud
Complete all side missions
Upgrade max health
Buy something from Ollie Snake
Catch a fish
Reunite the Wisps
Find Walrus Sr's mask
Kill a Mimic
Destroyed all Vile blooms
Find Ella
Destroy Dr Crow's research
Defeat the Vile
Reunited the band
Threw a party
Drained the sewers
Kill two enemies with a counter
Kill 300 creatures