Here is the full list of all 53 Beyond the Long Night achievements.
Beat an encore run in the party hat
Escape the Long Night
Defeat Sara
Discover the invisible gate in the Sanctuary
Discover the secret combination within the strange dimension
Find the Annoying Child awake in the Strange Dimension
Beat a run in the party hat
Reach the strange dimension
Discover all three runes in the monuments
Choose every type of stone at the monuments
Find one of the old diary entries
Discover the Ear Horn
Engrave a cow statue
Meet Sara
Get the annoying child to recognise you after you return from the Overworld
Speak to Pickles after returning from the Overworld
Beat a run in the explorer hat
Open all of the Annoying Child's shops
Reach the Sanctuary
Meet Tetchy and Dopey
Reach Hope's Peak
Meet Archie
Meet the Pilgrim
Return to the Dark Mountain after your first death.
Meet Umpa
Meet Eebi
Meet the Annoying Child
Discover the Storm
Reach the Forbidden Temple
Meet Pickles
Meet Bobbins
Return to the farm after the cows escape
Engrave all of the cow statues
Give the Annoying Child enough shiny stones to make a golden bust of themselves
Escort Tetchy and Dopey to the Sanctuary
Find Tetchy's remains after they escape to the Overworld
Find the Pilgrim after they leave the altar room
Learn everything you can from Archie
Find the remains of Archie after they escape to the Overworld
Find Archie after they fail to escape to the Overworld
Discover all of the old diary entries
Discover every Upgrade and Superpower in the game
Beat an encore run in the explorer hat
Beat a run in the mushroom hat
Beat an encore run in the mushroom hat
Beat a run in the iron hat
Beat an encore run in the iron hat
Beat a run in under 25 minutes
Beat a run in under 25 minutes without taking any damage
Beat a run without using your Superpower
Beat a run without collecting any upgrades
Beat a run using your main bullets weapon 100 times or less
Beat a run having visited every room on the map