With the iPhone 3G S and latest iPod Touch, Apple upgraded its smartphone and media players into what may become the most mainstream gaming devices in history. The App Store's most popular category is games, which makes up approximately 20% of its total inventory and is one of the primary drivers of sales. The new iPad hints at Apple's even greater interest in fashioning new, more compelling gaming experiences. Top 50: No. 2 
The continued expansion of Xbox Live has successfully blurred the console gaming experience with Internet entertainment. This full-featured network enables 20 million living rooms worldwide to play video games and chat with friends, update Facebook statuses, watch Netflix, create and sell games, even download entire Xbox 360 games. Top 50: No. 48 
It's one of the first successful iPhone-only game publishers, but Ngmoco's business model is what really sets it apart. After making millions of dollars on for-pay games, Ngmoco has decided to produce only free games and to integrate them with its Plus+ game-play network. Plus+ makes possible nearly frictionless in-app purchasing ("Buy this collar for your digital pet dog") and multi-user play. Top 50: No. 38 
4. Infinity Ward
The maker of the violent, controversial, but hypersuccessful Modern Warfare 2 racked up $550 million in revenue in the video game's first five days on sale last fall and more than $1 billion in the first two months. Which makes Modern Warfare 2 the top-selling game of 2009  and already one of the most successful of all time. One key behind its success: Infinity Ward used feedback from its 60,000 Twitter followers to help shape game play.
One of the Asian virtual-goods giants  and the only one that's also making inroads in the United States. The company's online games, including Maple Story (more than 90 million players worldwide) and Combat Arms, are bigger than World of Warcraft. Today, more than 30,000 retailers -- including Target, Blockbuster, and Walmart -- sell prepaid cards with Nexon's virtual currency.
Its Flash multimedia platform, which reaches more than 350 million computer users , has spawned an explosion in homemade games: roughly 14,000 of them across thousands of portals such as Kongregate and Newgrounds. Flash is also powering the very popular social games on sites like Facebook.
With The Beatles: Rock Band, the creators of the musical video-game genre  reached what could be considered its artistic pinnacle: great gameplay, amazing songs, and a focus on music history. The Beatles' sales totaled 1.7 million units worldwide in 2009, relatively strong given the overall weakness in the music-video-game genre.
The Radeon Eyefinity, the flagship product of ATi, the graphics-card division of chip maker AMD , can power six widescreen displays for the ultimate in immersive gaming experience. Running high-resolution games on Eyefinity has become a key metric for such game design. ATi's next-generation Fusion chip, which cheaply combines a graphics chip and a CPU onto one die, could single-handedly make gaming possible on a whole host of inexpensive devices that were too slow before, such as netbooks, tablets, and low-end PCs.
9. Rockstar Games
To continue the momentum of Grand Theft Auto IV, this game developer  created two downloadable add-ons that not only provided a variety of new game play, extending the value of the game, but also pushed the storytelling capacity of the medium. GTA IV has continued to be a sales juggernaut, selling more than 13 million copies worldwide.
10. Muteki Corp.
The model of the new game developer, Muteki is small, fast, and self-sufficient. Developer Ryan Evans and business partner Bryan Sawler are best known for building Topple 2, Ngmoco's Apple Design Award-winning game. Evans and other young game makers can build an entire iPhone game start-to-finish in about a month and make millions for a publisher.