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