Here is the full list of all 30 10 Second Ninja achievements.
Kill two enemies with one shuriken
Press restart before the timer has even begun
Shots... Shots Shots Shots Shots - die on spikes five times in a row
Complete the tutorial.
Get your first star rating.
Skip a cutscene.
Fiddle around with the settings.
Finish every world.
Finish every world with 3 stars.
Finish a level with 0.03 or less from your next star rating (or 3 star the entire game)
Die over 50 times
Restart over 500 times.
Toggle off the leaderboards OUT OF SHAME
Spend 5 seconds or more without touching the ground
Wander around a level for its duration without murdering anything.
Try firing your shurikens in a boss fight.
Go into the light.
Drop a falling block on an enemy's head
Make an icicle fall on an enemy's head
Finish the first world
Finish the second world
Finish the third world
Finish the fourth world
Finish the fifth world
Finish the first world with a 3 star rating
Finish the second world with a 3 star rating
Finish the third world with a 3 star rating
Finish the fourth world with a 3 star rating
Finish the fifth world with a 3 star rating
Finish Hard Mode and bleed the game dry for content