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