The advent of smartphones has opened up an entire new range of platforms for game development, particularly for independent game developers. The iPhone's App Store model has been enormously successful, with a recent estimate of $2.4 billion in annual sales.

From a developer's perspective, app stores have the incentive of a distribution channel with powerful search and marketing capabilities. They also provide an intermediary that handles the logistics of selling and downloading -- generally for a cut of 30%.

You've probably heard the Cinderella stories of developers like Steve Demeter, whose triangular variant on match-3 games, Trism, reportedly earned him $250,000 in just two months in the iPhone App Store. Take also Ethan Nicholas' iShoot, which reportedly earned $600,000 in a single month. With the gold rush mentality and the iPhone's undeniable success with the App Store, why would a game developer choose to make a game for any other smartphone platform?

About six months ago, I started developing games for Google's Android OS, somewhat by chance. A friend who works for Google gave me a G1 developer's phone as a gift. At that point, I hadn't even heard of Android. In the process of learning about the OS, I came across the Android SDK, and downloaded it to give it a spin. I was instantly hooked.

While iPhone apps are written in Objective C, the Android SDK uses relatively more programmer-friendly Java. The iPhone store charges developers $99 a year to distribute their apps, while Android has a one-time $25 fee for developers. And the review process for iPhone apps grows increasingly lengthy -- sometimes weeks or more -- and it's somewhat arcane. Android apps go live as soon as the developer hits the publish button. Google handles the review process post-hoc, and is much more lax in terms of content.

With the greater ease of producing and distributing apps through the Android Market, why aren't game developers large and small clambering to produce quality games for the system? There are a number of reasons, but number one is, of course, money.

Mobile ad company AdMob released its July 2009 report (pdf) which notes the following:

45 million estimated combined iPhone and iPod Touch users, compared to 3 million Android users

50% of iPhone users bought at least one paid app during a month period, compared to 19% of Android users

The estimated market value of the iPhone App Store is about $200M per month, compared to an estimate of about $5M per month for the Android Market

So a major part of the equation is pure size. But another factor is the population makeup of Android users and their perception of the platform. The iPhone user population is likely much more diverse, with a greater cross-section of users representing more diverse demographics, while the Android user population is still likely predominantly tech-centric early adopters. Since Android is an open-source system, the perception may also be that the software that runs it should follow the same model. Thus many users may be reticent to spend money on apps.