Here is the full list of all 71 Golden Light achievements.
Get every memento and open the final door
Complete 500 floors total
Enter the Murder Room on MEATZONE
Enter the White Room on MEATZONE
Kill 1000 monsters total
Throw 500 gold at Son
Kill your Meat Bro in Co-op while having Traitorous Bastard memento.
Complete 20 floors without dying
Enter the Val Room on Meat Zone
Kill Scourge directly
Enter the Torture Room on MEATZONE
Make 1000 gold
Kill She in the flashback
Kill 500 monsters total
Enter the Murder Room on Meat War
Enter the Val Room
Find a multy barrel shotgun
Make 500 gold
Collect Huge Chin and Nose with Teeth mementos in one run
Kill Castle directly
Kill Maneater directly
Kill Gut Divers directly
Kill anyone with your Huge Chin
Kill Eye Taker
Kill an Eyetaker with Meat Spear
Kill a monster with a Vein Whip
Kill Meall directly
Enter the White Room on Meat War
Complete 100 floors total
Enter the Field Room on MEATZONE
Destroy 50 walls total
Save her
Enter the Field Room on Meat War
Enter the Torture Room on Meat War
Put your hands into the talking toilet
Kill Needles directly
Collect Marv, Third Lung and Pulp mementos in one run
Complete 50 floors total
Bring a rose to Val
Make 200 gold
Destroy a wall by eating an item
Kill a monster with a Tommygun
Make 100 gold
Kill a monster with a Shotgun
Kill Carre directly
Buy a key from Golden Eye Taker
Lose an eye
Find 3 Golden Meats total
Kill 100 monsters total
Buy a key from Pile of Meat
Complete 20 floors total
Finish any floor without taking damage
Complete 5 floors without dying
Complete any floor without using your weapons once
Collect 25 keys total
Eat a fire item
The Gut hates you
Meet Rose for the first time
Find your first Golden Meat
Kill a monster with a pistol
Read a special note
Ressurect your Meat Bro in Co-op
Complete 1 floor in Co-op
Burn a monster to death
Kill a monster with a Revolver
Complete 3 floors total
Die
Kill a monster with a Pipe
Eat a poisoned item
Kill a monster with a Map
Kill a monster with an Axe