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