Shainiel Deo is one of the driving forces behind the new wave of so-called casual games: titles featuring relatively simple graphics and straightforward game play, which can be played a minute or two at a time on a mobile device or social website.

The 36-year-old CEO has built Australia’s Halfbrick Studios into one of the top casual-game publishers on the strength of Fruit Ninja, an addictive game in which players slice through a barrage of produce by swiping a finger across a touch screen, developing their skill as the fruit flies faster and thicker. Since the 99-cent game was released in April 2010, more than 10 million people have downloaded it.

Deo has seen casual games expand a once almost negligible market share to become a juggernaut: according to the Entertainment Software Association, 47 percent of the most frequently played online games are casual games, and they dominate the best-selling-app charts for both iPhones and Android devices.

Deo founded Halfbrick in 2001 in Brisbane, Australia, and started developing games for children that relied on content and characters licensed from TV shows and movies. These games were designed primarily for the video-game console market and were distributed online through the PlayStation Network, Xbox Live Arcade, and various websites. But the iPhone pushed casual games into the mainstream in 2007, prompting him to focus on original titles: in addition to Fruit Ninja, Halfbrick has a small stable of such games, including the popular Age of Zombies. “When mobile took off, the market aligned with our strengths,” he says, referring to Halfbrick’s experience with online distribution and simple game mechanics for children’s games.

See the rest of our Business Impact report on The Business of Games.

Mobile-app stores also gave independent developers across the globe access to a worldwide audience, enabling a small outfit like Halfbrick to compete head-on with multinational entertainment conglomerates.

Halfbrick now designs games primarily for mobile devices. The formula is simple: focus on a core game mechanic (e.g., Fruit Ninja’s finger swipe), whittle the code to a tiny footprint suitable for the limited battery life and processing power of a mobile device, and polish the presentation to a high gloss. For Fruit Ninja, Deo says, “we wanted it to be very simple … We knew that we had something special when we started showing our friends and family. They wouldn’t want to hand the phones back.”

For now, Halfbrick releases its titles on the iPhone first and rolls them out to other platforms as momentum builds. Deo looks forward to simultaneous Android-iOS releases, and he expects to add other platforms before long, including promotional versions that can be played in a Web browser, either in Flash or in HTML5.

Mobile technology has also revolutionized the gaming business model. Where Halfbrick used to be solely dependent on its distributors for sales, it now has a variety of revenue channels: selling games outright, giving away free games that are supported by in-game advertisements, and selling virtual goods within games themselves. Deo says that in-game purchases now account for 60 percent of Halfbrick’s revenue.

Just as going mobile gives game developers more control over revenue, it also puts them in charge of marketing, formerly a job for third-party publishers who license titles from developers and then take responsibility for promoting a game and getting it into stores. “Development is 50 percent,” Deo says, “but if you want to be successful, promotion takes up just as much resources. We have to build relationships with the press and platform holders. We need to build trailers and viral videos. We have to do community management to make sure we’re supporting and cross-promoting.”

The extra trouble is more than offset, Deo believes, by the opportunity to innovate in a burgeoning market. What he finds most exciting is the nexus of mobile, social, and cloud computing, which could allow users of future games to create their own levels and share them with other fans. Still, even as the technology becomes capable of delivering richer, more complex experiences, Deo remains committed to casual games: simple, direct, addictive entertainment.