One Button Game

This is  a one-button timing game prototype.

Press "Space" when a ball reaches the center.
Correct color and timing increase the score.
Pressing at the wrong time or with the wrong color costs a life.

Reach 50 points to win.
Lose all lives to lose the game.
Use the "Retry" button to restart. 

Video: 

Screenshots:

Playtest Question: 
Did the speed of the balls and the calibration timing create a sense of challenge?