Here is the full list of all 20 The MISSING: JJ Macfield and the Island of Memories achievements.
Acquire every donut.
Read all of F.K.'s hidden texts after finishing the game.
Jump over that black thing!
Read all of the texts from the past.
Find every Sleepy.
Read a hidden text from F.K. after finishing the game.
Select Continue after the ending and start a new run.
Complete the game.
Don't get too addicted to your phone.
Reach the top of the clock tower.
Escape danger.
Fall off a bridge.
Get run over by a train.
Crane operation is dangerous work.
Escape from something scary.
Find the first Sleepy.
Chat with F.K. for the first time.
Let the strange deer empower you.
Awaken at the campground.
First, you need to find Emily.