text:  The player begins with three lives ( power @-@ ups and rings add more ) , which are lost when Sonic collides with hazardous enemies ( or objects ) without rings , falls off @-@ screen or exceeds an act 's ten @-@ minute time limit . <unk> acting as checkpoints allow Sonic to return to the most @-@ recently activated post when he loses a life . If he loses a life as a result of time running out but has another life , the timer will reset to 0 : 00 when he returns to the checkpoint . If all lives are lost at any point in the game , the game over screen will appear ( when the player can return to the beginning of the act with three lives , if they have any continues ) . 
  