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