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