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