Thank you for your comments.
To Wozowski:
Before I finished the game, someone who played it tell me the game is too easy. So I add 6 more difficult levels at the end and set the life limitation.
Actually I found that knowing when to use 'reset' button is interesting and challenging too. Sometimes you will miss a chance of winning by resetting too early. But you may also lose a life for being late on resetting.
 "Circle Master 2: Gravitation"){kind=icon}
 "Circle Master"){kind=icon}