The term 'Part of the Game' can refer to four different vessels used in naval warfare. The first is a DESTROYER, which is a fast and maneuverable warship designed to escort larger vessels in a fleet and defend them against smaller, powerful attackers. The second is a SUBMARINE, which is a vessel that operates underwater and is used for stealthy reconnaissance and attack missions. The third is a patrol boat, which is a small, lightly armed vessel used to protect a nation's coastline from enemy ships. Finally, an aircraft carrier is a large warship that carries and launches aircraft for offensive and defensive operations. All of these vessels are essential components of naval warfare and are considered part of the game.