Full list of all 31 Decay achievements worth 1,000 gamerscore. It takes around 2-3 hours to unlock all of the achievements on Xbox One.
Get out of the bathroom in Part 1.
Defend yourself in Tic Tac Toe.
Complete Part 1.
Dial the number found on the access card to Oswald Estates.
Complete the video game in Shining Gate Software's office.
Unlock the piano in Part 2.
Solve the puzzle with all the symbols in Part 2.
Complete Part 2.
Solve the cryptogram in Part 3.
Reach the goal in the labyrinth game in Part 3.
Repair the doll in Part 3.
Complete Part 3.
Unlock the iron box in 10 moves in Part 4.
Complete the picture shuffle puzzle in Part 4.
Arrange the colored balls in 60 moves in Part 4.
Disarm the bomb in 40 seconds in Part 4.
Balance across the hole as true master in Part 4.
Collect all diary pages in Part 4.
Collect all coins in Part 4.
Collect all handcuffs in Part 4.
Use all handcuffs on Anne in the basement in Part 4.
Get the best ending in Part 4.
Find out all the different endings in Part 4.
Complete Part 4.
Make use of the pen in Part 2.
Arrange the pieces of the photo in Martin's office in Part 2.
Open the passage to the secret room in Part 4.
Reach the goal in the dark maze in Part 4.
Meet Chelsea in Part 4.
Open the hatch on the floor in Part 4.
Arrange the letters in the basement in Part 4.