 If the player misses a door, he or she will not be allowed to go any further after a certain point.Each player has a health gauge that shows the amount of damage that his or her character is allowed to sustain; when the gauge reaches zero, the player will lose a life.Many additions have also been made to the play mechanics such as four-way scrolling (the original could only scroll vertically), new moves and weapons, multiple characters and a two-player cooperative mode.