Here is the full list of all 17 Monochrome World achievements.
You got the first color.
I don't want to go down the ordinary road. (Clear certain stage at less than 80% colorfill, except for Stage 1-10)
This is poisonous. Your body won't grow big no matter how much you eat it.
Escape from Big One.
Win against Big One.
Likely to become a master swordsman soon.
Endless Challenge
There is a meaning to picking up coins yourself.
I will never stop! (Achieve 150 combos)
Natural disasters are scary.
The robot is already dead. (Destroy 300 robots)
It's time for revenge!
Utilized Pond of Memory.
Won the battle against The Eye
I must fill every empty space (Get perfect clear 59 times)
I finished everything and became the first light.
Collected all achievements.