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