Here is the full list of all 22 Project MALLOW achievements.
Beat every level in Chapter 1
Beat every level in Chapter 2
Beat every level in Chapter 3
Beat every level in Chapter 4
Beat every level in Chapter 5
Beat every level in Chapter 6
Beat every level in Chapter 7
Beat every level in Chapter 8
Jump 100 times
Jump 1,000 times
Jump 10,000 times
Die 10 times
Die 100 times
Die 1,000 times
Get 1 star
Get 240 stars
Get all 480 stars
Find all 70 tapes
Collect all accessories
Reach the goal while on fire
Complete 15 levels in a row, without dying or restarting
Spend 60 minutes falling