Here is the full list of all 47 Telecube Nightmare achievements.
Defeat 200 enemies
Complete all the worlds
Complete the game and collect all the stars
Defeat 100 enemies
Get 40 stars
Get 37 stars
Get 38 stars
Get 39 stars
Get 36 stars
Get 33 stars
Get 34 stars
Get 35 stars
Defeat 50 enemies
Get 30 stars
Get 31 stars
Get 32 stars
Complete 10 levels
Get 27 stars
Get 28 stars
Get 29 stars
Get 25 stars
Get 26 stars
Get 22 stars
Get 23 stars
Get 24 stars
Get 21 stars
Get 19 stars
Get 20 stars
Get 16 stars
Get 17 stars
Get 18 stars
Complete 5 levels
Get 13 stars
Get 14 stars
Get 15 stars
Get 10 stars
Get 11 stars
Get 12 stars
Get 9 stars
Get 6 stars
Get 7 stars
Get 8 stars
Get 3 stars
Get 4 stars
Get 5 stars
Get 1 star
Get 2 stars