Episodic content actually seems like a very natural progression for iPhone games, considering the regularity and ease of their updates through the App Store system.

I don't think anyone expected chapter-based games to become quite so popular, but this new trend for serialising our gaming habits is something that's going to have a massive impact on the future of the industry.

ICS Mobile has been in touch to let us know that its unique tower defence game Navy Patrol: Coastal Defense will be receiving the third chapter in its strategic plot, in which brand new attack submarine turrets will be employed to take out a vast aerial invasion of a new map called Caprina Islands.

Entitled Air Force Supremacy, this next update will also include a revamped interface, integrated iPod music controls, Facebook connectivity and a collection of bug fixes.

Navy Patrol: Coastal Defense has seen a massive boost in popularity recently after being featured in Apple's 'What's Hot' section, and Chapter III is expected to be with us any day now, so keep an eye on your App Store updates.

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