Here is the full list of all 48 Half Past Impossible achievements.
Die 10 times
Completed the tutorial
A new contender
Completed level 2
Completed level 3
Completed level 4
Defeated the boss on world 1
Completed level 5
Completed level 6
Completed level 7
Completed level 8
Defeated the boss on world 2
Completed level 9
Completed level 10
Completed level 11
Completed level 12
Completed level 13
Completed level 14
Completed level 15
Completed level 16
Completed the game!
You are legendary! - L
You are legendary! - E
You are legendary! - G
You are legendary! - N
You are legendary! - D
You are legendary! - !
You're The Guy!
Die 100 times
Die 500 times
Checked out the store page!
Welcome - W
Welcome - E
Welcome - L
Welcome - C
Welcome - O
Welcome - M
BOSS3