This guide lists all Steam achievements for Undusted: Letters from the Past and how to unlock them.
Story Achievements
These are earned by progressing through the main storyline of the game. These are typically unavoidable and tied to cleaning each object.
Icon
Name
Description
A Dusted Key
Clear Level 1.
Bunny Ears!
Clear Level 2.
Shattered
Clear Level 3.
Shining in the Darkness
Clear Level 4.
A Little Ditty
Clear Level 5.
No Means No
Clear Level 6.
Snow-capped
Clear Level 7.
Left Behind
Clear Level 8.
In Darkness Found
Clear Level 9.
Words Gone Astray
Clear Level 10.
Shouldn’t Have Said That
Clear Level 11.
What Was Left Inside
Clear Level 12.
What Had Always Been There
Clear Level 13.
Unexceptional
Clear Level 14.
If I Had Called First…
Clear Level 15.
Nothing Left Undusted
Clear Level 16.
Letters From the Past
Finish the story. Watch the last cinematic of the game..
Grinding Achievements
Just have to play the game.
Icon
Name
Description
A Shining Start
Clean 4 objects to 100%.
Nearly Spotless
Clean 8 objects to 100%.
Every Last Speck
Clean all objects to 100%.
Simple and Clean
Clean all items to 100% using only sponge and toothbrush. If you’re thinking, “What do I do with glass objects? i have to use the cloth with those!!”. Yep, it’s going to take a while. I think in these cases it’s better to use the toothbrush or sponge rather slowly, rather than scrubbing quickly. Try it out.
The levels with “extra” tools are 7, 8, 11, 12, 13, 14, 16 and 17. Level 6 does not count towards the completition of this achievement.
Patience is an Art
Clean any object using only the air blow gun.
No Help Needed
100% any stage (excluding tutorial) without hints.
Hidden/Secret Achievements
This part will contain spoilers.
Icon
Name
Description
It’s Still Not Working!
While hints are unavailable, try to use them 3 times
Clean as an Ocarina
Play notes in order on the ocarina on LEVEL 5. You have to play a major scale in order on the ocarina using the brush. If you don’t have the slightest musical ear, follow the next image. 
Squeak!
Use the cloth. The achievement will unlock when you use it at LEVEL 7.
Let It Snow
Turn the snow globe into a winter wonderland. On LEVEL 7, clean the glass and shake the snow globe.
Too Pretty to Clean
Clean off a flower. You will get this achievement on LEVEL 7.
With These Hands
Push the pocket watch button to open it on LEVEL 8.
Echo… Echo… Echo…
Listen to the drum echo in the MIDI controller on LEVEL 9. Turn on the MIDI controller with the switch on top, then turn the knob on the right all the way to the left and press the buttons.
Air it Out!
Use the air blow gun. The achievement will unlock when you use it at LEVEL 11.
Dad’s Final Song
Listen to the music box play on LEVEL 11. You must turn the crank on the side of the music box to hear the melody.
Say Cheese!
Take a photo with the camera. On LEVEL 12, open the camera lens and the flash with the red button on the back of the camera, then press the shutter button to take a photo.
Like She Once Did
Press the typewriter keys 5 times on LEVEL 14.
An Excuse to Call You
Listen to the easter egg on the telephone on LEVEL 15. For all those who in their short lives have never seen, let alone used, a rotary phone, this is what you need to do to make a call. First, lift the receiver, then rotate it clockwise from the number you want to dial to the metal stop. Let go of the dial and wait for it to rotate it back to its original position. Repeat for each number an then wait. To get the achievement you need to dial 217. It can be a little complicated at first, remember that every time you correctly dial a number, the game will let you know with a beep sound.
Etched in Heart
Clear the hidden object. After completing the story (cleaning all objects and watching the final cinematic), level 17 will unlock with a new object to clean. Clean it and you’ll unlock the achievement.