Here is the full list of all 16 In Between achievements. It takes around 6-8 hours to unlock all of the achievements on Windows.
There's more than one route to follow.
Complete five acceptance loops
Watch the credits
Complete Acceptance
Complete Depression
Complete Bargaining
Complete Anger
Complete Denial
Do a successful gravityzone jump
Die 100 times
Complete Tutorial
Reach one MindImage
Complete all levels
Complete the game without dying
Reach all MindImages
Find the 5 hidden glimmers of hope.