name	iOS
logo
screenshot
website
developer	Apple
family	Mac OS X/BSD/Unix-like
released	June 29, 2007
frequently updated	yes
language	Multilingual
kernel type	Hybrid (XNU)
ui	Cocoa Touch (Multi-touch, GUI)
programmed in	C, C++, Objective-C
license	Proprietary EULA except for open-source components
working state	Current
supported platforms	ARM (iPhone, iPod touch, iPad, and 2nd gen Apple TV)
package manager	}}

iOS (known as iPhone OS/iPod Touch OS before June 2010) is Apple's mobile operating system. Originally developed for the iPhone, it has since been extended to support other Apple, Inc. devices such as the iPod touch, iPad and Apple TV. Apple, Inc. does not license iOS for installation on third-party hardware. , Apple, Inc.'s App Store contains more than 500,000 iOS applications, which have collectively been downloaded more than 15 billion times. In the last quarter of 2010, it had a 26% share of the smartphone operating system market in terms of units sold, behind Google's Android and Nokia's Symbian. As of May 2010, it accounted for 59% of mobile web consumption—not including the iPad—in North America.

The user interface of iOS is based on the concept of direct manipulation, using multi-touch gestures. Interface control elements consist of sliders, switches, and buttons. The response to user input is immediate and provides a fluid interface. Interaction with the OS includes gestures such as ''swipe'', ''tap'', ''pinch'', and ''reverse pinch'', all of which have specific definitions within the context of the iOS operating system and its multitouch interface. Internal accelerometers are used by some applications to respond to shaking the device (one common result is the undo command) or rotating it in three dimensions (one common result is switching from portrait to landscape mode).

iOS is derived from Mac OS X, with which it shares the Darwin foundation, and is therefore a Unix-like operating system by nature.

In iOS, there are four abstraction layers: the Core OS layer, the Core Services layer, the Media layer, and the Cocoa Touch layer. The current version of the operating system (iOS 4.3.5) uses roughly 650 megabytes of the device's storage, varying for each model.

History

The operating system was unveiled with the iPhone at the Macworld Conference & Expo on January 9, 2007, and released in June of that year. At first, Apple marketing literature did not specify a separate name for the operating system, stating simply that the "iPhone runs OS X". Initially, third-party applications were not supported. Steve Jobs argued that developers could build web applications that "would behave like native apps on the iPhone". On October 17, 2007, Apple announced that a native Software Development Kit (SDK) was under development and that they planned to put it "in developers' hands in February". On March 6, 2008, Apple released the first beta, along with a new name for the operating system: "iPhone OS".

Brisk sales of Apple mobile devices kindled interest in the SDK. The previous September, Apple had released the iPod touch, which had most of the non-phone capabilities of the iPhone. Apple also sold more than one million iPhones during the 2007 holiday season. On January 27, 2010, Apple announced the iPad, featuring a larger screen than the iPhone and iPod touch, and designed for web browsing, media consumption, and reading iBooks.

In June 2010, Apple rebranded iPhone OS as "iOS". The trademark "IOS" had been used by Cisco for over a decade for its operating system, IOS, used on its routers. To avoid any potential lawsuit, Apple licensed the "IOS" trademark from Cisco.

Version history

Apple licensed the trademark for "iOS" from Cisco Systems (which owns IOS), the same company with which Apple had earlier settled a dispute over the "iPhone" trademark.

Apple released iOS 4 on June 21, 2010, three days before the iPhone 4, in an effort to reduce the strain on Apple's servers. iOS 4 is the first version of the OS to be a free upgrade on the iPod touch; Apple had charged $4.99 for earlier upgrades. Apple previously announced that iPad users with 3.x software would receive a free upgrade to the next major (4.x) release.

iOS 4.0.1 includes a fix to the reception signal strength indicator(s). It was released on July 15, 2010, the day before Apple hosted a press conference to discuss its response to the widely publicized iPhone antenna issues. Apple also released iOS 3.2.1 for the iPad which tweaks the tablet's Wi-Fi connectivity, video playback, and copy-and-paste for PDF attachments, among other updates.

iOS 4.0.2 for iPhone and iPod touch and iOS 3.2.2 for the iPad were released on August 11, 2010, to fix a pair of security vulnerabilities.

iOS 4.1 for the iPhone and iPod touch was released on September 8, 2010; the update fixes some bugs reported by users, improves battery life and adds a new feature called Game Center, which allow gamers to multiplay, upload high scores and to unlock achievements (though, Apple removed Game Center from the iPhone 3G due to reports on slow performance) and adds initial support for the iPod touch 4th Generation and the Apple TV 2G. iOS 4.1 also updated carrier settings which in the US was AT&T; 8.0 and enabled toggling Check Spelling On/Off. iOS 4.1 also adds HDR photography, a feature that only the iPhone 4 is capable of using. TV Show Rentals are available on the iTunes US Store. iOS 4.1 also adds a new feature called Ping which is a social music network and discovery tool.

iOS 4.2 was released to developers on November 8, 2010. It was never released to the public as a Wi-Fi bug was found during the limited release. Apple then issued two more golden master releases. Finally, Apple released iOS 4.2.1 to the public.

iOS 4.2.1 was released on November 22, 2010 with support for all Apple A4 devices, 3rd-, and 2nd-generation devices, with the exclusion of the Apple TV. It brings initial support of iOS 4.x to iPad, plus AirPlay and AirPrint to all compatible devices. It also contains minor changes to the YouTube app and alters the multitasking animation. On iPad, the side switch now acts only to mute system sounds. As a known major bug, this version seems to hinder the usage of the Camera Connection Kit on the iPad.

thumb|right|200px|iOS 4.3.X home screen on an iPad 2 with Wi-Fi + 3G. iPad 2 is currently the only iOS device with the Photo Booth app.iOS 4.2.5 was released as a demo version for the CDMA version of the iPhone 4. This iPhone 4 variant was released for Verizon Wireless customers in the US on February 10, 2011, but pre-ordering was available for qualified Verizon Wireless Customers on February 3. The version released with the phone, 4.2.6, has some slight UI changes specifically for the CDMA version of the phone, including a "Personal Hotspot" switch in the Settings app, a service which has to be activated by the carrier in order for the feature to be usable. This will be able to be purchased from Verizon as a separate plan, as is currently possible on other smartphones.

iOS 4.3 beta was released to developers on January 12, 2011, and the gold master on March 3, 2011. iOS 4.3 includes finger gestures which let you switch between apps, return to then home screen, and open up the multi-tasking panel. This feature is only available to developers.

iOS 4.3 was released to the public on 10 March 2011, one day before the iPad 2 was available in the United States. In addition to earlier features, the public release of iOS 4.3 includes many new features such as a Nitro JavaScript engine in Safari, making Safari run up to twice as fast. iTunes Home Sharing also received a major revision in iOS 4.3; it allows users to connect to their home Wi-Fi networks and stream content from iOS devices to speakers, TVs and other devices, or vice versa. Personal Hotspot for iPhone 4 is a new feature to GSM iPhones (previously released with the Verizon iPhone) that allows the user to create a Wi-Fi network with an iPhone 4 and provide Internet access for up to five other devices on Verizon Wireless, three on AT&T;. This will be available for both US iPhone 4 carriers, AT&T; and Verizon Wireless. In addition, the side button on the iPad is now customizable, with users able to use it either as a system sound mute or as a screen rotation lock.

iOS 4.3.1 (4.2.6 for CDMA iPhone) was released on March 25, 2011. It addressed an occasional graphics glitch on the fourth generation iPod touch, resolved bugs that were related to activating and connecting to some cellular networks, fixed image flickering when using an Apple Digital AV Adapter with some TVs, and resolved an issue authenticating with some enterprise web services.

iOS 4.3.2 (4.2.7 for CDMA iPhone) was released on April 14, 2011. It fixed an issue that occasionally caused blank or frozen video during a FaceTime call, issues that prevented some international users from connecting to 3G networks on iPads, and contained the latest security updates.

iOS 4.3.3 (4.2.8 for CDMA iPhone) was released on May 4, 2011 in response to the discovery of location services caching in iTunes. The update reduces the size of the cache, prevents it from being uploaded during synchronization, and erases it when location services are turned off.

iOS 4.3.4 (4.2.9 for CDMA iPhone) was released on July 15, 2011 in response to JailbreakMe 3.0 from comex (a developer). It uncovered a userland PDF exploit that is fixed in this update.

iOS 4.3.5 (4.2.10 for CDMA iPhone) was released on July 25, 2011. Update says "A security issue has been resolved with certificate verification."

iOS 5.0 and its features were announced on June 6 at the WWDC 2011 keynote address. The expected release date is believed to be in the third quarter of 2011. iOS 5 will introduce the iCloud service and the Notification Center, as well as improvements to native apps such as Camera. The operating system also features new applications, such as the "Reminders" app and "Newsstand", an application resembling Folders and iBooks. Unlike other applications, Newsstand is the first native application to actually run on the homescreen. "iMessage" is an application that allows iPod touch, iPhone, and iPad users to communicate, much like a chat service only used between these devices. The iMessage feature has been integrated into the SMS/MMS application used originally on the iPhone models. The iPod application on the iPhone and iPad has now been split into the Music and Video application, just like on the iPod touch. According to Apple, the new OS has over 200 new features.

Features

Home screen

The home screen (rendered by "SpringBoard") displays application icons and a dock at the bottom of the screen where users can pin their most frequently used apps. The home screen appears whenever the user switches on the device or presses the "Home" button (a physical button on the device). The screen has a status bar across the top to display data, such as time, battery level, and signal strength. The rest of the screen is devoted to the current application.

Since iOS version 3.0, a Spotlight Search function has been available on the home screen, allowing users to search through media, applications, emails, contacts and similar files.

Folders

With iOS 4 came the introduction of a simple foldering system. When applications are in "jiggle mode", any two can be dragged on top of each other to create a folder, and from then on, any other 10 "apps" can be added to the folder using the same procedure (maximum folders can handle is 12 on iPhone and iPod touch and 20 on iPad). A title for the folder is automatically selected by the type of applications inside, but the name can also be edited by the user.

Notifications screen

In the iOS 5 update, the notifications feature has been redesigned. Notifications now collate in a window which can be dragged down from the top of the screen .

Included applications

The iOS home screen contains these default "apps". Some of these applications are hidden by default and accessed by the user through the Settings app or another method—for instance, Nike+iPod is activated through the Settings app.

	Name	Usage	First Appearance
iPhone			iPod Touch	iPad
Phone
	E-mail client
	Web browser
iPod	Portable media player

	Name	Usage	Version Included
iPhone			iPod Touch	iPad
Messages
Calendar	Calendar
Photos	Photo viewer
Camera	Camera, Camcorder		Video recording and auto-focus iPhone 3GS (3.0) onwards	720p HD video iPhone 4 (4.0)	High dynamic range imaging>HDR iPhone 4 (4.1)	Crop, red eye fix, auto enhance and photo rotate (5.0)		Crop, red eye fix, auto enhance and photo rotate (5.0)(4th generation only)		Crop, red eye fix, auto enhance and photo rotate (5.0) (iPad 2 only)
YouTube	YouTube video streamer
FaceTime
Stocks	Yahoo! Finance
Maps.	Google Maps
Weather	Yahoo! Weather
Voice Memos	Voice recorder
Notes	A simple note-taking program
	A newspaper and magazine store
Reminders	A to-do list application
Clock	World clock, stopwatch, alarm clock and timer
Calculator	Calculator (includes scientific version)
Settings	Settings
iTunes
	To buy iOS apps
Compass	Compass
Contacts	Address/phone book
Nike + iPod	Records the distance and pace of a walk or run; can connect to Nike + iPod sensor
Game Center	Allows the user to play multiplayer games with other users, track in game achievements and view leaderboards.
Photo Booth	A camera application with added special effects

All of the utilities, such as voice memos, clock, calculator, and compass are in one folder called "Utilities" in 4.0. Many of the included applications are designed to share data (e.g., a phone number can be selected from an email and saved as a contact or dialed for a phone call).

The iPod touch retains the same applications that are present by default on the iPhone, with the exception of the Phone, Messages, Compass and Camera (prior to the 4th generation) apps. The "iPod" App present on the iPhone is split into two apps on the iPod Touch: Music, and Videos. The bottom row of applications is also used to delineate the iPod touch's main purposes: Music, Videos, Safari, and App Store (Dock Layout was changed in 3.1 Update). For the 4th Generation iPod touch, it includes FaceTime and Camera, and the dock layout had changed to Music, Mail, Safari, Video. As of iOS 5.0 (to be released to the public in September to November of 2011), "iMessage" will be available on all iOS devices running iOS 5. iMessage is effectively a version of the iPhone Messages app that sends free text or multimedia messages to other iOS devices (similar to BlackBerry Messenger).

The iPad comes with the same applications as the iPod touch excluding Stocks, Weather, Clock, Calculator, and the Nike + iPod app. Separate music and video apps are provided, as on the iPod touch, although (as on the iPhone) the music app is named "iPod". In iOS 5, the iPod app will be replaced by Music and Video apps on all devices. Most of the default applications are completely rewritten to take advantage of the iPad's larger display. The default dock layout includes Safari, Mail, Photos and iPod.

Multitasking

Before iOS 4, multitasking was limited to a selection of the applications Apple included on the devices. Apple worried that running multiple third-party applications simultaneously would drain batteries too quickly. Starting with iOS 4, on 3rd-generation and newer iOS devices, multitasking is supported through seven background APIs: # Background audio # Voice over IP # Background location # Push notifications # Local notifications # Task finishing # Fast app switching

Switching applications

Double-pressing the home button activates the application switcher. A scrollable dock-like interface appears from the bottom, moving the contents of the screen up. Choosing an icon switches to an application. To the far left are icons which function as music controls, and a rotation lock. Holding the icons briefly makes them wiggle (similarly to the homescreen) and allows the user to quit the applications.

Game Center

Game Center is an online multiplayer "social gaming network" released by Apple. It allows users to "invite friends to play a game, start a multiplayer game through matchmaking, track their achievements, and compare their high scores on a leader board."

Game Center was announced during an iOS 4 preview event hosted by Apple on April 8, 2010. A preview was released to registered Apple developers in August. It was released on September 8, 2010 with iOS 4.1 on iPhone 4, iPhone 3GS and iPod touch 2nd generation through 4th generation. Game Center made its public debut on the iPad with iOS 4.2.1. There will be no support for the iPhone 3G and original iPhone. However, Game Center is unofficially available on the iPhone 3G via a hack.

Development

The applications must be written and compiled specifically for iOS and the ARM architecture. The Safari web browser supports web applications as with other web browsers. Authorized third-party native applications are available for devices running iOS 2.0 and later through Apple's App Store.

SDK

On October 17, 2007, in an open letter posted to Apple's "Hot News" weblog, Steve Jobs announced that a software development kit (SDK) would be made available to third-party developers in February 2008. The SDK was released on March 6, 2008, and allows developers to make applications for the iPhone and iPod touch, as well as test them in an "iPhone simulator". However, loading an application onto the devices is only possible after paying an iPhone Developer Program fee. Since the release of Xcode 3.1, Xcode is the development environment for the iOS SDK. iPhone applications, like iOS and Mac OS X, are written in Objective-C.

Developers are able to set any price above a set minimum for their applications to be distributed through the App Store, of which Apple will take 30% of the revenue (the other 70% goes to the developer). Alternately, they may opt to release the application for free and need not pay any costs to release or distribute the application except for the membership fee.

Jailbreaking

iOS has been subject to a variety of different hacks centered on adding functionality not supported by Apple. Before the 2008 debut of the App Store, the primary reason for jailbreaking was to install third-party native applications. Apple said it would not design software updates specifically to break these native apps (other than applications that perform SIM unlocking); however, with each iOS update the jailbreak appears to no longer work.

Since the arrival of the App Store and third-party applications, the focus of the jailbreaking community has shifted. A major focus of jailbreaking is allowing theming, using emulators and community-made tweaks like multitasking, Adobe Flash player, accessing the iPhone file system, and customizing the SpringBoard further. Multitasking is only natively supported on 3rd-generation and newer iOS devices, and applications on the official App Store are not allowed to modify the look of the OS, hence the need for jailbreaking.

Digital rights management

The closed and proprietary nature of iOS has garnered criticism, particularly by digital rights advocates such as the Electronic Frontier Foundation, computer engineer and activist Brewster Kahle, Internet-law specialist Jonathan Zittrain, and the Free Software Foundation who protested the iPad's introductory event and have targeted the iPad with their "Defective by Design" campaign. Competitor Microsoft, via a PR spokesman, has also criticized Apple's control over its platform.

At issue are restrictions imposed by the design of iOS, namely DRM intended to lock purchased media to Apple's platform, the development model (requiring a yearly subscription to distribute apps developed for the iOS), the centralized approval process for apps, as well as Apple's general control and lockdown of the platform itself. Particularly at issue is the ability for Apple to remotely disable or delete apps at will.

Some in the tech community have expressed concern that the locked-down iOS represents a growing trend in Apple's approach to computing, particularly Apple's shift away from machines that hobbyists can "tinker with" and note the potential for such restrictions to stifle software innovation. However, there are some outside of Apple who have voiced support for the iOS closed model. Facebook developer Joe Hewitt, who had previously protested against Apple's control over its hardware as a "horrible precedent", has subsequently argued the locked apps in the iPad are akin to web applications and provide added security.

See also

iOS version history

List of iOS devices

References

Further reading

External links

iOS Dev Center – on the Apple Developer Connection website

iOS Reference Library – on the Apple Developer Connection website

Category:Mach Category:Multi-touch Category:Smartphones Category:2007 introductions

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Title	Sonic Adventure
Developer	Sonic TeamSonic Team USA (international)NOW Production (additional DX staff) Sega Studios Shanghai (360/PS3 ports)
Publisher	Sega
Designer	Takashi Iizuka (Director/Level Designer)
Writer	Akinori Nishiyama
Artist	Kazuyuki Hoshino (Art Director)Yuji Uekawa (Character Design)
Composer	Jun Senoue (Sound Director)Kenichi Tokoi Fumie Kumatani
Released	}}

PlayStation Network: }} |genre = Platformer |modes = Single-player, multiplayer |ratings = |platforms = Dreamcast, Nintendo GameCube, Microsoft Windows, Zeebo, PlayStation 3 (PSN), Xbox 360 (XBLA) |media = Optical disc, Download |requirements = Windows XP or better, 800 MHz Pentium III, 32 MB Geforce 2 or Radeon SDR, 1.2 GB hard drive space }}

is a video game developed by Sonic Team and released on December 23, 1998, in Japan by Sega for the Dreamcast. One of its development titles was ''Sonic RPG'' (although the final product was an adventure game, not a standard RPG). The final updated edition, known as ''Sonic Adventure International'', was released on September 9, 1999, in North America, October 14, 1999, in Japan and Europe, October 18, 1999, in Belgium, the Netherlands, and Luxembourg, and December 1, 1999, in Australia. It has sold over 2.5 million copies, making it the best-selling Dreamcast game. It was the first ''Sonic'' game on a sixth generation console.

An enhanced port was released in 2003 as ''Sonic Adventure DX: Director's Cut'' (see below) for the Nintendo GameCube and in 2004 for Microsoft Windows. The game was ported to Xbox Live Arcade on September 15, 2010 and PlayStation Network on September 20, 2010. The game was featured on ''Dreamcast Collection'', a four-game bundle released in 2011.

Gameplay

This game is the first in ''Sonic'' series to feature free-roaming 3D gameplay. The game is divided into three types of stages: Action Stages, Adventure Fields and Subgames. The division of Action Stages and Adventure Fields was a serious departure from previous ''Sonic'' games. In addition, unlike the previous game in the series, ''Sonic Adventure'' has six different characters to choose from: Sonic, Tails, Knuckles, Amy, Big and E-102 Gamma; each with their own style of gameplay. Only Sonic is playable at first, but other characters are made available after encountering them in his story. When all stories have been completed, a final story is unlocked.

Sonic's stages involve high speed gameplay, whilst Tails' stages require him to reach the end of the level before Sonic (and in one case, Robotnik) does and Knuckles' stages see him searching the area for shards of the Master Emerald. All three of these returning characters retain a lot of their trademark moves from previous Sonic games. Amy's stages require her to escape from the E-100 Zero robot chasing after her, Gamma's stages involve shooting through levels to reach a target and Big's stages involve fishing for his friend, Froggy.

Action Stages are the main playable levels for each character, where the player must face various enemies in order to complete their respective goals. Adventure Fields split up the action, where players can explore the surroundings to advance the plot, discover new levels or search for items which enhance a character's ability (for example, the Light Speed Shoes allow Sonic to run across a path of rings). Subgames deviate from the main gameplay of the character, which include minigames such as kart racing and snowboarding. Players may also find hidden Chao Gardens, which allow them to raise Chao, a sort of virtual pet. Chao can be taken with the player by downloading the minigame ''Chao Adventure'' to their VMU, or in the GameCube version, a Game Boy Advance with ''Sonic Advance''. The player can also raise their stats by giving them small animals that they found by defeating the robots, which improves their performance in Chao Races. There are also eggs hidden throughout the Adventure Fields which can produce special types of Chao.

By playing through Action Stages and Subgames, searching through the Adventure Fields or winning Chao Races, players can earn Emblems. In the case of Action Stages, each one has three Emblems, which can be earned by replaying the stages and fulfilling certain objectives, such as beating the level within a time limit. In ''Sonic Adventure DX'', these can unlock hidden extras such as Game Gear games.

Synopsis

Characters

Much of ''Sonic Adventure'' centers on Sonic, a hedgehog who has the ability to run at supersonic speeds, and Miles "Tails" Prower, a two-tailed fox who often accompanies Sonic on his adventures; they are the main characters of the game who are in pursuit of Robotnik /DR.Eggman. Supporting characters include Knuckles, an echidna who guards the Master Emerald on Angel Island, Amy Rose, a pink hedgehog who has a crush on Sonic, and newcomers Big the Cat and E-102 Gamma. Big is a purple, noticeably overweight cat who must rescue his best friend Froggy who became possessed by Chaos' tail, and swallows Big's "lucky charm", a Chaos Emerald, which causes him to mutate. Gamma is one among a series of robots designed by Eggman to take orders without question. After an encounter with Amy, he suffers a malfunction and gains a "conscience". He then turns his aim to destroying his robotic brothers and freeing the animals trapped inside them.

The main antagonist of the game is Dr. Robotnik, also known as Dr. Eggman because of his round body shape, who has formulated a new plan to conquer the planet, this time not relying on his robots alone, but employing a strange liquid creature known only as Chaos. Chaos also serves an antagonistic role in the game, and is the guardian of the Chao. He is apparently water or a plasma-like material and changes form after consuming a Chaos Emerald. After consuming all seven Chaos Emeralds, he turns into Perfect Chaos, which Eggman aims to use in order to conquer the planet. The main antagonist of Amy's story is E-100 Alpha (better known as Zero), the first E-100 series robot who is a large green robot and is considered the prototype. Zero is one of Dr. Eggman's Robots sent to find Amy's friend Birdie. He follows Amy wherever she goes hoping to capture her and the bird. At one point he succeeds but Amy is rescued by E-102 Gamma. Eventually Zero is defeated by Amy on the Egg Carrier.

Dr. Eggman's E-Series of robots play a large role in Gamma's story, as he is one of them, and is out to destroy or "save" the others. All of them have letters of the Greek alphabet as part of their name. E-101 Beta is a black robot with two gun arms. He is the first boss in E-102 Gamma's side of the story, and is later upgraded into E-101 Beta Mk II, who is Gamma's fifth and final boss. E-103 Delta is a blue robot who is Gamma's second boss, waiting at the end of Windy Valley. E-104 Epsilon is an orange robot who is the third boss of Gamma's side of the story and is fought at the end of Red Mountain. E-105 Zeta is a purple robot who is Gamma's fourth boss and is located at the end of Hot Shelter. While at first humanoid, Zeta is altered into a cylinder-like form with several turrets made up of a few Dreamcast machines.

Friendly characters who are non-playable include Tikal, a mysterious female echidna who appears whenever Sonic, Tails, Knuckles, Amy, E-102 Gamma and Big are sent back in time. She is trying to stop her father, Pachacamac, from stealing the Chaos Emeralds from the Master Emerald shrine. She appears mostly in the form of a pink ball of light called a Hint Orb. A major feature of the game are Chao, small creatures who can be raised in the Chao Gardens and play a supporting role in the story.

Plot

Centuries ago, the planet was bestowed the seven Chaos Emeralds. These mystical gems were infused with ancient unlimited power, and consequently it did not take long before wars erupted over who would control them. Amongst the seven Chaos Emeralds was the Master Emerald, the controller of the seven Chaos Emeralds with the power to either amplify or negate the power within them. Whilst the seven Chaos Emeralds and the Master Emerald rested peacefully, a Chao inhabiting the land nearby the Shrine of the Emeralds accidentally made contact with the holy water surrounding it. The water transcended the Chao into a peaceful creature known as Chaos, who with the ability to control water henceforth became the guardian of the Shrine. Some time after, a tribe of Echidnas, led by Pachacamac, angered Chaos by attempting to steal the Chaos Emeralds, ruining the sanctuary it was protecting and destroying the many Chao living there. Chaos, in his fury, summoned the negative powers of the seven Chaos Emeralds to transform into Perfect Chaos and proceeded to slaughter the Echidna race. Pachacamac's daughter, Tikal, had pleaded with Pachacamac not to disturb the Shrine of the Emeralds but her efforts were futile. After Perfect Chaos left the shrine to enact revenge on the entire world, Tikal prayed to the Master Emerald to seal her and Chaos within in.

In the present day, Dr. Eggman learns of the legend surrounding Chaos through a mural in the lost world. Believing it to be true, he creates his flying fortress, the Egg Carrier, seeks out the Master Emerald and shatters it, freeing Chaos in the process while interrupting Knuckles's job of protecting it and forcing him to collect the shattered pieces. Eggman's goal was to control Chaos, and use its destructive powers to collect the Chaos Emeralds and conquer the entire world, turning it into Robotnikland. To help him, he has created the E-Series robots, a group of powerful robots powered by animals placed inside them and programmed to obey him. Soon after, Chaos makes his way into the Mystic Ruins where Big is sleeping. Big's friend, Froggy, ends up swallowing Big's lucky charm, the yellow Chaos Emerald, and bitting off Chaos's tail which causes him to grow his own tail. Big then begins chasing down Froggy. As Sonic returns from an adventure, he sees the police trying to attack Chaos who has arrived into Station Square. He fights and defeats him, but Chaos escapes. Later at night, Eggman creates E-102 Gamma, the second of his E-100 robots. Eggman tests Gamma's skills by having him do target practice and battling E-101 Beta in order to join the team of the Egg Carrier. The next morning, Tails is out testing a new prototype plane but malfunctions and crashes. Sonic rescues him, and Tails shows him a Chaos Emerald he found which gets stolen after a battle with Dr. Eggman upon arriving at the Mystic Ruins. Amy's story begins in mid-story of all the characters. Remembering old times with Sonic, the Egg Carrier flies over Station Square, and a bird smacks into Amy. As soon as the bird drops, a robot named ZERO chases Amy. After they learn of Eggman's plans, Sonic and his friends spring in to action to stop Eggman and they all start their own separate, but intertwined, journeys for the Chaos Emeralds.

Sonic has defeated Eggman and Chaos, Tails has stopped Eggman from bombing Station Square with a missile, Knuckles has restored the Master Emerald, Amy has rescued a small bird and his family from the clutches of Eggman and his robotic minion Zero, Big has rescued his best friend Froggy, and Gamma has rescued his robotic brothers from Eggman's clutches, destroyed by a last resort point blank blast from his elder "brother" E-101 Beta MK-II and releasing the bird during the process.

However, shortly afterward, Angel Island falls once again, and Eggman is attacked by a surviving Chaos. Meanwhile, noticing that Angel Island has fallen once again, Knuckles decides to go to Sonic with the Chaos Emeralds for advice, when suddenly he finds Eggman on the island, bitter and defeated. Knuckles asks him what happened, to which Eggman responds "This is terrible! C-Chaos is...", before being attacked once more alongside Knuckles by Chaos, who steals the latter's six Chaos Emeralds.

Elsewhere, Sonic and Tails take notice that Angel Island has fallen once again, and hurry to the scene, where they find Eggman and Knuckles lying on the ground. Knuckles then reveals to Sonic and Tails that Chaos stole and absorbed the six Chaos Emeralds he was in possession of. Eggman flies off in a hurry, going to his secret hangar to use the Egg Carrier 2. Sonic and Tails then decide that they must retrieve the final Emerald before Chaos, when suddenly, Sonic is teleported to the past where he witnesses former echidna chief Pachacamac and his warriors attacking the Master Emerald shrine, with the chief's daughter Tikal pleading to them not to attack the shrine before they are all killed by Chaos, who absorbs the seven Emeralds and attempts to destroy the world. Sonic then returns to Angel Island, where he and Tails return to Tails's plane the Tornado 2, which uses the seventh emerald as a power source. However, they arrive too late and Chaos retrieves the seventh Emerald before they do.

Meanwhile, in Station Square, Chaos transforms into his final form, Perfect Chaos, and floods the entire city. Sonic arrives, where he witnesses Eggman trying to attack Chaos in the Egg Carrier 2. However, Chaos immediately destroys it. Tikal then appears, explaining that Chaos's heart is filled with anger and sadness and the negative energy of the Chaos Emeralds flows through him. Chaos drains the Emeralds' power completely, leaving all power of the Emeralds useless. Tails, Knuckles, Amy and Big arrive with all 7 Emeralds and their collective positive energies along with Sonic's good heart enables him to re-ignite the Emeralds' positive powers. Sonic transforms into Super Sonic and neutralizes Perfect Chaos. Chaos is not destroyed completely, but his heart is filled with joy, happiness and forgiveness. Tikal takes Chaos back with her, but leaves the Chao to live peacefully with humans. Sonic runs off into Station Square and Angel Island is put back to its original state high in the heavens.

Development

Development of ''Sonic Adventure'' began around April 1997 with a development team of 30 members. Then Sega employee Yuji Naka had been unhappy with prior treatment of Sonic, especially in the Sega Saturn racing game ''Sonic R''. After several titles for the Mega Drive, he worked mainly on the game ''Nights into Dreams...''. However, learning of the Dreamcast brought him a renewed interest in creating ''Sonic'' games. The development team focused on graphics and high resolution for this game, with Naka reflecting that "[w]e have pushed the Dreamcast as far as we can at present".

Naka aimed to create levels that would take the player at least five minutes to complete, yet retain similar gameplay to the Mega Drive titles. Following the creation of the basic level maps, Naka wondered "why don't we use this map for other characters?" This led to the introduction of Big and E-102. The development team conducted surveys of fans to ensure that the final product—especially the characters—would please them. Sega made it a top priority to keep the game hidden until shortly before its release. Despite these efforts, screenshots were leaked onto the Internet in mid-1998. Naka presented the game to ''Edge'' in mid-August, and official announcement fell on August 22 in Japan.

Sonic Adventure also introduced a drastic shift in the overall art style of the games that continued to be used over the next few years. The more detailed, modernized redesigns of Amy Rose and Dr. Eggman probably best reflect this. The characters resemble graffiti art in their official artwork, striking more dynamic and extreme poses. In the game, there were some unused items, such as the Sky Dragon from the level Sky Chase, the so-called unused levels, Final Egg and Lost World. The level Emmerald Coast is going to be included in the upcoming Sonic Generations.

Music

Head composer Jun Senoue brought a new sound to the ''Sonic the Hedgehog'' series with this game, and as such it features many different styles of music such as jazz, rock, techno, pop and country. Each heroic player character (aside from Gamma) also has an instrumental motif that later translates into a vocal theme song that plays during the end credits of their story. The game contains vocal performances from Tony Harnell, Karen Brake, Marlon Saunders, Dread Fox, Ted Poley, Nikki Gregoroff and Johnny Gioeli, whom the latter would later join Senoue to form the band Crush 40. The development team preferred the use of "hot, funky, and rock 'n' roll" music over the traditional techno-based music present in earlier ''Sonic'' games.

Ports

In 2003 an enhanced port was released for the GameCube and Windows titled . The Windows version was at first released only in Japan and Europe, but later saw a limited North American release. ''Sonic Adventure DX'' includes a Mission Mode, which included 60 missions to complete throughout the Adventure Fields and Action Stages. It also contains an unlockable compilation, which comprises twelve Game Gear games featuring Sonic and friends. Also, if all Emblems are collected, then the player can play as Metal Sonic. Also, Cream the Rabbit makes a cameo appearance in certain parts of the game. Reviews were generally less positive than those of its Dreamcast predecessor, scoring more than 20% lower than the original release.

On June 10, 2010, Sega officially announced ''Sonic Adventure'' would be released on both the Xbox Live Arcade and PlayStation Network in Fall 2010. ''Sonic Adventure DX'' was released on Steam, as the first in a series of Dreamcast titles to be released as digital downloads. Additional features will include enhanced graphics, surround sound, online leaderboards, achievement/trophy support and unlockable Avatar Awards, consisting of a ''Sonic Adventure'' T-Shirt and Sonic's "Speed Shoes".

''Sonic Adventure'' was released on Xbox Live Arcade on September 15, 2010, while the PlayStation Network version was released on September 20, 2010. The initial release is based on the PC version of ''Sonic Adventure DX'' despite the game simply being called "''Sonic Adventure''". The DLC package, simply titled "Sonic Adventure DX Upgrade", has launched alongside the game on XBLA, for 400 Microsoft Points, and $4.99 on PSN, effectively making the entire ''Sonic Adventure DX'' 1200 Microsoft points ($15). It upgrades the game to include all of the features from the GameCube and PC versions with the exception of the Game Gear games and Dreamcast DLC.

Reception

The reception at the time of original Dreamcast version was overwhelmingly positive, including reviews from GameSpot and GameSpy being above 90%. The current Game Rankings average ranking is 88%. It became one of the few Sega All Stars games. In Japan, it received an excellent 38 out of 40 from ''Famitsu''. Although criticized for its camera system, framerate issues, and fishing stages with Big, the game was still highly praised for retaining the fast and enjoyable gameplay that Sonic was known for in 2D as well as the game's graphics, multiple character storylines, and soundtrack. Brandon Justice of IGN rated the game an 8.6/10, criticizing various glitches and voice acting while praising the game's visuals and gameplay. On the other hand, ''GamePro'' gave it a 5/5 saying, "Sonic is fun, fast, and a great reason to purchase a Dreamcast". The game has sold over 2.5 million copies worldwide, making it the best-selling Dreamcast game. This includes one million sold in the United States.

The PlayStation 3 and Xbox 360 ports received less favorable reviews. While some critics viewed it as a good piece of nostalgia, others criticized the lack of improvements and the game's more noticeable age, with IGN giving it a score of 3.5 out of 10, calling it "so fundamentally flawed that it borders on unplayable", making it the lowest scored Sonic game on the site since ''Sonic and the Black Knight''. 1UP.com gave it a D rank, criticizing its lack of improvements and touchy controls. ''Retro Gamer'' gave the Xbox 360 port 63%.

References

External links

Sonic Retro page on this game

Official website

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