Here is the full list of all 43 Mr. Bree+ achievements.
Get all other achievements
Beat all levels without dying
Complete all levels in all game modes
Beat 40 levels without dying
Beat 40 levels in hardcore mode
Watch the credits cutscene to the end
Beat 20 levels in hardcore mode
Beat 5 levels in hardcore mode
Start a level in hardcore mode
Skip the last cutscene
Get 75% of all achievements
Defeat the slaughterhouse boss
Press the red button!
Collect all bad memories
Beat level 24 in less than 29 seconds
Beat 20 levels without dying
Beat your best time 20 times
Collect 20 bad memories
Beat your best time 10 times
Stay still for a while
Enter the first slaughterhouse level
Defeat the forest boss
Get 50% of all achievements
Beat 40 levels
Beat 5 levels without dying
Die on the first level
Quit a level
Perform your first double jump
Get Double Jump
Get Wall Jump
Beat 20 levels
Die 100 Times
Die 50 Times
Beat the tenth level
Die 10 times in the same level
Get Run
Collect 5 bad memories
Die 5 times in the same level
Beat 5 levels
Get Crouch
Collect the first bad memory
Die 1 time
Get Jump