HTML and CSS Reference
state. First, it checks to see that there are no longer any particles on the screen. This ensures
sure that all the player's missiles have finished their lives. We do this so that we can check
forcollisionsbetweenthe playerMissiles andforcollisionsof rocks against saucers .This
way the player might earn an extra ship before playerShips-- is called.
When the particles and missiles have all left the game screen, we subtract 1 from the
playerShips variable and then switch to GAME_STATE_GAME_OVER if the playerShips num-
ber is less than 1 .