Here is the full list of all 42 Pleh! achievements.
The base game contains 41 achievements, and there is 1 DLC pack containing 1 achievements.
This door was not one of them
I wish we could stay like this forever
Cracked the mainframe
Thank you VERY much for playing!
I respect your wishes.
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Misery
Find all 10 hidden transcripts
Thank you for watching the credits!
I should have known.
Carry on.
I bet you think you're so funny.
Anxiety
Please don't take me away...
A clock, a piano, and a girl. What do they all mean?
Sing happy birthday twice
Remember to wash your hands!
Agony
Desperation
Please leave me alone
Dullness
Stop taking them away from me!
Consider this your final warning
I AM EVERYWHERE
Disappointment
Type "null" when null
10.17
Demotivation
Depression
Walk backwards for 10 seconds
Push the chair 50 times
Push the chair 10 times
Afterlife
Suicide
Please come back...
Beat Pleh!
Press H to begin
Quit the game at the warning screen
Push the chair 100 times
Push the chair 500 times
Push the chair 1500 times
Complete the new content update