Game Screen
Number of remaining grenades : When on board a Slug this will display remaining canon shots.
Slug defense : Your Slug will explode when this reaches zero.
Number of rescued prisoners : Resets each time your character dies.
Remaining time : When this reaches zero your character will lose a life.

When you find a tied up prisoner and save them you can receive ammunition or a weapon as a reward. Additionally, a bonus will be added to your score at the end of the stage based on how many prisoners you saved.