Here is the full list of all 24 Summer of '58 achievements. It takes around 2-3 hours to unlock all of the achievements on Windows.
You have fed the cats.
The dead and the buried…
You have reached an abandoned hospital.
You have collected all the photos in the camp, during correspondence.
Have you packed all your things.
You picked up a pocket watch.
You've found the evidence.
Have you read the director's story.
The second night in the camp came.
Have you found a photo of the camp.
Did you wake up after the impact.
You were hit on the head.
The first night in the camp came.
Russian wooden toy.
Welcome to the pioneer camp.