the mid-2000s. Nokia had installed Snake onto its line of mobile phones since the Nokia 6110 in 1997. Similar manufacturers of phones, personal digital assistants and other devices also included built-in games, but these were designed to pass the time and not engaging. As phone technology improved, a Japanese mobile phone culture grew around 2003 with games ranging from puzzle games and virtual pet games that use camera phone and fingerprint scanner technologies to 3D games with PlayStation-quality graphics. Older arcade-style games became very popular on mobile phones, which were an ideal platform for arcade-style games designed for shorter play sessions. Namco made attempts to introduce mobile games to Europe in 2003. Nokio released its N-Gage, a hybrid phone/handheld game system, in 2003 but had limited success compared to Nintendo's Game Boy Advance. Around 2005, the first smartphones were available on the market, which offered data connectivity alongside phone services. Carriers licensed games to be made available for sale on a storefront, but this did not catch on due to the disparate storefronts and differences between phone models, and the games could not be as sophisticated as on consoles or handhelds due to limited hardware on the smartphones. In 2007, Apple, Inc. introduced its iPhone which was technologically more advanced than other smartphones on the market, and unveiled its App Store in 2008 through which new apps could be purchased. With the App Store, developers, once signed up as a partner, could then develop and publish their own apps through the store. This allowed developers of any size to participate in the App Store marketplace. Google, which developed the competing Android mobile operating system, released its own version of an app store in 2008, later named as Google Play in 2012. The use of Apple's and Google's app storefronts for gaming applications quickly took off with early successes like Angry Birds and Bejeweled. When Apple introduced in-app purchases (IAP) in October 2009, a number of developers found ways to monetize their mobile games uniquely compared to traditional games, establishing the freemium model where a game is usually free to download and play but players are encouraged to speed up their progress through IAPs. Games like Candy Crush Saga and Puzzle & Dragons, both in 2012, established this approach as highly-profitable business models for mobile games. Many of the social network game developers worked to either integrate a mobile version with