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