[Gamasutra takes a look at the state of the market for iOS, Android, and Windows Phone 7, marrying statistics with commentary from PopCap, Gameloft and Glu to uncover the present and future of the markets for both phones and tablets.]

Ever since developers began churning out hits for the iPhone in 2008, the mobile gaming market has exploded, and the stigma of games on mobile phones has all but disappeared. Since the initial success of iOS -- which continues to be a strong market thanks to the continued popularity of the iPhone and now the iPad -- other platforms have popped up as well. Android now maintains a larger overall market share than Apple, while Microsoft continues its attempt to push into the mobile space with Windows Phone 7.

But which of these platforms is most viable right now? And how will that change going forward? Speaking to developers at PopCap, Gameloft, and Glu, Gamasutra explores the present and future of the ever-expanding smartphone and tablet gaming market.

iOS

Ever since the iPhone App Store debuted in 2008, games have been an important part of its success. Titles like Angry Birds and Cut the Rope have become household names, while indie success stories like Sword & Sworcery and Osmos are gaining prominence. Less than two years after the App Store launched, one billion applications had been downloaded, many of them games.

According to research firm Gartner, in 2010 Apple maintained nearly 16 percent of the smartphone market, with worldwide sales approaching 47 million units. That number is expected to grow even larger in 2011, with 19 percent market share and over 90 million devices in the hands of users. By 2015, analysts predict that there could be nearly 190 million iPhones sold to consumers.

And when it comes to the tablet market, Apple is in a relatively dominant position. In 2010 Apple owned more than 80 percent of the tablet market, with over 14 million iPads sold. And though that market share is expected to dip below 70 percent in 2011 thanks to a number of competing devices, the number of iPad users is expected to grow to nearly 50 million. In 2012 it could be 70 million, and in 2015 140 million.

So what is it that makes Apple's line of mobile gadgets so appealing? According to Mike Breslin, VP of marketing for Glu Mobile, the "frictionless e-commerce engine" that powers the App Store is a big attraction. Consumers get a better overall shopping experience, which in turn leads to higher sales and increased revenue for developers. And unlike other mobile marketplaces, the range of handsets and operating systems developers need to take into consideration is minimal, making development a relatively smooth process.

There are plenty of original games that have been very successful on the platform, but as the market grows and the sheer number of games available expands, brands are becoming ever more important for visibility. A new Angry Birds spin-off is sure to reach the top 10 sales charts, as is a new release from one of PopCap's stable of popular franchises.

"We are launching games that are adaptations of hugely successful products on the platform," explains Andrew Stein, PopCap's director of mobile product management. "So when we come to the App Store we're a known quantity. We've already sold millions and millions of copies of our existing games, so if we launch something new we can get visibility for those new products in the existing games."

This has allowed games like Bejeweled 2 and Plants vs. Zombies to remain best-selling titles even years after their initial release. PopCap currently receives around 30 percent of its revenue from mobile releases, with the largest chunk of that 30 percent coming from iOS.

But in the App Store's four years of existence, the model for releasing successful games has changed dramatically, shifting steadily towards a more service-based system. Instead of simply releasing a game for a set price and then waiting for the sales to come in, developers now need to regularly update games with content to ensure a steady stream of sales and a happy customer base.

According to Giordano Contestabile, PopCap's senior director of mobile product and business strategy, the market has shifted to a place where "sales of the game are not necessarily the primary revenue driver."

In-app purchases are becoming more and more common, and a large number of titles now shed their price tag all together, going the freemium route instead. This creates a space where sheer numbers become even more important: the more people who are playing your game the bigger the potential in-app sales are.

"Volume is the answer," says Breslin. "With the freemium model, the consumer consideration funnel broadens by multiples. If a game is good, it will succeed. If it's not good, it won't succeed.

"As a publisher and/or developer of freemium games, the goal is to get as many people to play your game as possible to allow for the social and viral hooks to work. So, it's easy to see how a freemium model that takes away the number one hurdle to a consumer, cost, is attractive to developers and publishers."

"That [shift to freemium] literally is changing the way games are designed, games are marketed, and it's changing the way games are maintained and operated," adds Contestabile. "So we don't have, anymore, a developer that develops a game, publishes it, and then sits back and waits for the revenue. It's actually a living product that they need to update and keep alive over the months and over the years."

For those games that do go the freemium route, there's a good chance that the ability to connect to social networks like Facebook could become a large factor in their success. Proper social networking integration provides more visibility for games, which is important to get noticed in an increasingly crowded marketplace.

However, that's not to say that all games will be free in the future. Gameloft has recently demonstrated that premium titles coupled with a subscription fee can be successful, as its iOS MMO Order & Chaos (which costs $6.99, as of this writing) managed to generate $1 million in revenue in its first 20 days. Though the developer is planning on testing the freemium waters this year, it will also be using a variety of payment structures going forward.

"We think that there's still a place for other types of business models: premium, paymium (small premium up front and in-app purchases), subscription-based models," explains Baudouin Corman, Gameloft's VP of publishing Americas. "These models are probably better adapted to more hardcore games or more niche products. It will be interesting to see how Apple makes these models coexist on the App Store."

Android

While Apple may be the focus for many, Google's Android mobile platform is slowly creeping up on it. The fact that there are more daily Android activations than iOS has forced developers to take notice, in spite of the platform's well-documented issues, such as fragmentation of hardware and inconvenient payment processes.

According to analysts, Android's share of the smartphone market will be around 40 percent this year, and could jump as high as 50 percent by 2012. That means that by the end of this year there are expected to be nearly 180 million Android-enabled smartphones in the hands of consumers, and that number could top 300 million by next year, and 500 million by 2015.

That dominance doesn't translate to the tablet market, however, where Android devices managed to account for just 14 percent of the market in 2010 with 2.5 million devices sold. However, that number is expected to grow quite a bit, with nearly 14 million tablets sold by the end of the year. And by 2015 analysts predict that Android tablets will be in striking distance of the iPad, with 113 million units sold, accounting for 38 percent of the tablet market.

Many developers initially took a wait-and-see approach, biding their time until the conditions of the market improved. PopCap, for instance, waited until the operating system reached version 2.2, which introduced the ability to save applications to an SD card. Gameloft first decided to enter the market when more powerful phones were released, allowing the developer to bring its high definition mobile games over to Android.

That being said, most developers still take an even more cautious approach to the platform, porting successful iOS titles to Android as opposed to developing original experiences. Generally speaking, games that sell well on iOS will also sell well on Android.

The rising profile of certain Android phones appears to be slowly changing this way of thinking... at least, in some instances. When Gameloft first launched BackStab, a high-profile 3D action game, it was a timed exclusive for Sony's brand new, PlayStation-branded Xperia Play device. Eventually the game made its way to iOS as well, but it was one of the few high-profile games to debut on an Android handset.

"Exclusivities on a platform are driven by business opportunities and technical features," says Corman. "If a game can only run on a specific Android hardware and/or if there's a good business reason then you'll certainly see more Android exclusive titles from Gameloft."

The one thing you will need to think about when releasing a game on Android, though, is where you want to sell it. Unlike Apple devices, which feature one unified store for purchasing apps, Android has many. In addition to Google's marketplace, Android apps can be purchased from places like Amazon and GetJar, or even rented from through services such as Exent's Gametanium.

While this can be daunting and sometimes frustrating, it can also give developers more power. For example, because PopCap wasn't entirely happy with the way the Android market was set-up, it decided to make the debut of Plants vs. Zombies on Android a timed exclusive for the Amazon app store.

"Amazon doesn't solve all of the problems and issues around the Android platform, but they do have a lot of experience in selling digital content," says Contestabile, of the decision to partner with Amazon. "They do have a very large database of credit cards, which means that if you are an Amazon store customer, the billing issue goes away, because with one click you just charge on your Amazon account.

"They do have a very powerful discovery and recommendation engine that they can deploy for Android games. And also, they have a very strong web presence through which they market PopCap products across every platform. You can buy PC games, and console games, and Android games, etc. And so we also felt it was a good way for us to promote products across different platforms."

The relative flexibility of Android also opens up potential opportunities that aren't possible on iOS. For instance, Contestabile says that PopCap could potentially partner with a hardware manufacturer to embed its games on phones, bypassing the various app stores all together.

But if there's one constant complaint about Android, it's that users don't like to spend money. Instead of the one-click purchasing that's available on iOS, Android users are faced with more friction, which leads to fewer sales. That's a problem now, but not necessarily a permanent one. Developers are already seeing consumer behavior change, and many believe that over time the Android user will eventually become much like its iOS counterpart.

The two already have something in common, though, and that's the freemium shift. And because a large part of being successful in freemium gaming is simply getting your game played by as many people as possible, multi-platform games are key. This makes exclusives less likely, but doesn't preclude the idea of a game debuting on Android before spreading to other platforms. Glu's Gun Bros, for example, launched initially on Android before making its way to both Facebook and iOS.

"As it's our focus to deliver top quality freemium mobile games no matter the platform, it's more beneficial to have our games be available on all appropriate platforms vs. just one," says Glu's Breslin.

Windows Phone

Which brings us to Microsoft. Despite its best efforts, the computer giant hasn't managed to take a big bite out of the smartphone market. Launched late last year, Windows Phone 7 features both a unique operating system and integration with Xbox Live, but it's still a relatively small slice of the mobile pie. In 2010 MS had less than five percent of the smartphone market with around 12 million Windows Phones sold, though that number is expected to double by the end of 2011; by 2015 Windows Phones could account for almost 20 percent of the market.

"It certainly hasn't resonated with consumers as anyone would like," says PopCap's Stein, who uses a WP7 device as his everyday phone. "Given the install base of Windows Phone devices, our games have actually sold quite well, and it monetizes very well for customers who have a Windows Phone. There just aren't enough of them right now."

PopCap has been with the platform from the beginning, releasing Bejeweled Live as a launch title, and will be bringing Plants vs. Zombies to the platform in the future as well.

It's not just the small market share that's holding back WP7, as PopCap's Stein also says that there are technical issues that could potentially be holding back developers from creating games for the platform.

"Microsoft insists on a different development paradigm with C sharp instead of C++," he says. "So it's a lot more work for developers to support Windows Phone as a platform."

That being said, with its next update, code-named Mango, Microsoft is adding new features that will enhance the gaming experience on WP7, both from a developer and user perspective. Starting this fall, developers will be able to access cameras, sensors, and gyroscopes built-in to handsets, as well as utilize contact and calendar information, among other changes.

Whether or not these changes are enough to entice consumers -- and developers -- to the platform remains to be seen. But it seems clear that in order to become a viable platform for game development, WP7 phones simply need to be in the hands of more users.

In Conclusion

It seems that as the platforms continue to grow and mature, the differences between them become increasingly small. At least, that appears to be the case with iOS and Android. Both platforms are steadily shifting towards a more service-based economy, with a focus on in-app purchases as the major revenue source.

WP7 may be dragging behind in terms of consumer adoption rates, but Microsoft is clearly making efforts to improve the platform from a gaming perspective, and this could very well lead to WP7 being a viable option for developers. And having all three platforms, and potentially others, become successful can only be a good thing.

"The more viable and meaningful platforms that succeed," says Breslin, "the better we as an industry will do."

But no matter which platform you're developing for, there is still one genre of game that could potentially be the next big thing in mobile gaming. It's a genre that's rife with potential and creative opportunities, and is also one of the few that can only truly be done on a mobile device. But it hasn't produced a blockbuster hit just yet.

"We're starting to see interesting and fun and commercially viable location-based games," says Contestabile, "and I think new titles are going to take advantage of these kinds of opportunities because the platform lends itself to new and interesting stuff, in a sense."