A little over a month after the App Store's download tally was pegged at 14 billion during WWDC 2011, Apple's Philip Schiller has announced that users have already added an extra billion to that total.

Apple claims 15 billion apps have been downloaded from the App Store in the three years since it launched on iOS, with a total of 425,000 titles now available.

Of that app library, 100,000 are native iPad releases, with 200 million iOS users in all tapping into the firm's marketplace – the same array of figures detailed in June.

Thank you note

"In just three years, the revolutionary App Store has grown to become the most exciting and successful software marketplace the world has ever seen," added Schiller.

"Thank you to all of our amazing developers who have filled it with over 425,000 of the coolest apps and to our over 200 million iOS users for surpassing 15 billion downloads."

Apple hasn't revealed which app managed to clock up the 15 billionth download, though its press blitz naturally reflects the important role games have to play.

In particular, Infinity Blade from Epic Games has served as a popular poster child for the platform of late.

Epic performance

"Infinity Blade has been a runaway hit with customers around the world and we couldn't be more excited about our success on iOS devices," said Epic Games VP and co-founder Mark Rein, noting that iPad provides the studio with "an unparalleled mobile device for creating gorgeous, immersive games."

Epic has been a key flagbearer for iOS since Infinity Blade made its debut, helping the platform tap into a core audience in recent months.

It's an informal partnership that hasn't been without its rewards for the developer.

Rein recently revealed that Infinity Blade has generated $11.2 million net on iOS – a return that's equal to Gears of War on Xbox 360 when both the amount of time in development and size of the workforce is taken into account.