Here is the full list of all 25 Death Squared achievements.
Complete a Party level
Make All 4 players dance at same time
Die 50 times in a single level
Complete 9 levels in a row without dying
Complete 6 levels in a row without dying
Complete 3 levels in a row without dying
Skip the intro
Viewed the credits. Thanks!
Finish the Story
Complete 60 Story levels
Die 250 Times
Find a secret item
Complete 40 Story levels
Die A Lot More
Complete 20 Story levels
Complete 10 Story levels
Die 10 times
Customize your bot
Complete 1 Story level
Complete 10 Party levels
Finish the Party
Die 999 times
Find 5 secret items
Find 10 secret items
Make All 4 players die at same time