Ninja Gaiden is a side-scrolling platform game. There are six “Acts” that comprise 20 levels. Ryu’s strength is represented by a life bar, which goes down when he is hit by an enemy or projectile. A “life” is lost when the life meter is depleted or when Ryu falls off of the screen, or when time runs out.
The game is over when all lives are gone. The player may restart the level on which this occurred by continuing. At the end of every act, the player will fight a boss; bosses have life meters that the player drains with attacks. Each boss is one of the “Malice Four” – evil underlings of the Jaquio, the game’s main boss.