Here is the full list of all 22 What Happened achievements.
Collect every piece of Stiles’ memories.
Find all of Rose’s items.
Find the Condom.
See the bad ending.
See the good ending.
Find the secret ending.
Complete every ending.
Show the middle finger.
Break every ice statue in the Ice Halls.
Burn every sheet of memory in the Halls of Memories.
See every Limbo after being taken by the Hands.
Get eaten by the shark 20 times.
Avoid feeding the shark your own flesh.
Don’t drown Maya’s pictures
Find the hidden ending through the Limbo
Refrain from self-harm
Find Rose’s memories in the overgrown school
Find the secret ending right after getting humiliated in the art class
Ignore the mind in the pencil draft school
Find the secret ending in the overgrown school
Find and destroy your true enemy
Find the alternative ending in the chamber of doors