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