Here is the full list of all 18 Grayscale Memories achievements.
Take the elevator 3 times
Clear all the color chess before the storm come
Clear the text shooting game
Find the goal
Hit by the objects and loss the light balls more than 3 times
Tried more than 50 steps and still doesn't solve the puzzle
Hit by the light circles more than 3 times
Falling from the elevator and being sent back
Collecting all the messages in water
Step on the black/white switches more than 6 times
Hit by the objects more than 20 times
Hit by the attack wave 3 times
Start the game and play level 1
Find all the hidden messages
Reach the white ending
Reach level 7 in the infinite maze
Reach level 9 in the infinite tower
Open the treasure boxes 50 times