In the early phases of the project, Chaos Emeralds were researched in the hopes of applying their properties to living beings. These studies resulted in the development of Chaos Drives, small capsules of energy used to fuel the life support system of the "ultimate life form" prototype. This prototype, modelled in the image of a lizard, initially showed positive results: it possessed the abilities of regeneration, self-restoration, and self-reproduction. The researchers were thrilled, but as the creature continued to evolve, it became unruly and difficult to control. Concerns arose for the safety of the scientists and crew, casting new doubt on the research. Eventually, one or more unknown engineers involved with Project Shadow leaked information on the affair to GUN (Guardian Units of Nation), a government military organization.

   Political friction had already existed between GUN and ARK, and the military magnates - now terrified at Gerald's progress - jumped on the opportunity to suspend Project Shadow and shut down the research facility. They violently siezed control of the craft, evacuating all the residents while killing everyone involved in the research except for Gerald himself, who was incarcerated. Once ARK was cleared and the facilities frozen, troops sealed the prototype creature away in the deepest part of the colony. The whole coup d'état took less than a week. GUN's public explanation was that the ARK was evacuated due to a biohazardous accident on board, with all researchers lost in the disaster. Gerald was falsely accused of causing the "accident", and sentenced to death for his negligence. But there was one thing GUN didn't notice...

   As the bloody coup was underway, Gerald was already putting the finishing touches on another version of the ultimate life form: one vastly superior to the prototype. When GUN troops stormed the colony, the beleaguered professor entrusted his final creation to Maria, and instructed the two of them to make a run for safety in a hidden escape pod. Gerald, meanwhile, ran in the opposite direction to draw the troops' attention. Only later did he discover Maria's name on the list of casualties, which proved to be the last straw. The once great Pr. Robotnik, overcome with rage, became a man obsessed with revenge.

   50 years later: Dr. Eggman, having stumbled upon the journals of his late grandfather, bets this "ultimate life form" will succeed where Chaos failed. Armed with his new combat walker, the Doc breaks into a secret military base and awakens the fruit of grandpappy's research: Shadow the Hedgehog. Sonic is drawn into the fray after being framed by his charcoal-colored doppelgänger. Tails, ever the loyal sidekick, puts himself into the line of fire to help clear Sonic's name. Knuckles is busy going the rounds with Rouge the Bat, a government spy and freelance thief with an eye for jewels (particularly the Master Emerald). As events unfold, the 6 players break into 2 factions: the Hero side of Sonic, Tails, and Knuckles and the Dark side of Eggman, Shadow, and Rouge. Each seems to have his own agenda. None can imagine that they're pawns in a meticulously calculated plot for revenge from the grave. But as they're all about to find out, Eggman got more than he bargained for by tapping into Gerald's legacy...

   Gone are the showcase Adventure Fields of Sonic Adventure 1: Sonic 2's convoluted narrative consists strictly of Action Stages interspersed with cutscenes. Goals are primarily the same, though controls are a bit more intricate: press A to jump, B or X to perform a special action, and Y to toggle between the various special actions your character can perform. The control pad handles character movement while the L and R triggers manage camera rotation.

   New to the mix is an elaborate scoring system that becomes pivotal to unlocking the game's many secrets. Unlike previous iterations of the series, where high scores tend to be an afterthought, Sonic Adventure 2 encourages and rewards those who fine-tune their laps. Shave a few more seconds off your best time, bop one or two more enemies, grab an extra couple of Rings around that last corner: whatever it takes to edge your score up to a coveted A rank. Points are multiplied by linking stunts together in rapid succession. After a successful wave of tricks, the game rates your performance with some verbal praise: Good, Great, Nice, Jammin', Cool, Radical, Tight, Awesome, Extreme, or Perfect.

   There are 6 playable characters, though only half as many play styles:

Sonic and newcomer Shadow account for the high speed platforming desideratum. Sonic now has the ability to grab on to ledges and haul himself up, allowing him to reach higher platforms. The key to earning high scores is to chain attacks and stunts: use the Homing Attack to smash multiple enemies in succession or press A while flying off a ramp to perform an aerial trick that would make NiGHTS proud.

:: Sonic the Hedgehog ------------------------------------------------- Spin Attack (スピンアタック) -- Tap button A to leap into the air with a spin attack. The height of the jump is proportional to how long you hold the button down. Homing Attack (ホーミングアタック) -- Jump, then press the A button again while in midair to home in on the nearest enemy or Item Box. Somersault (サマーソルト) -- Tap B or X to roll forward with a brief somersault attack that can be used to smash wooden Containers or squeeze through tight gaps. Pick up the Flame Ring item and the Somersault becomes the more powerful Fire Somersault which can destroy iron Containers. Spin Dash (スピンダッシュ) -- Press and hold B or X to have Sonic rev up with a stationary spin, then release to dash off with a rolling attack. Grind (グラインド) -- Leap onto any narrow surface (such as a banister) and Sonic will make use of his new Soap shoes to grind along the length of the rail. Use the control stick for balance and hold B to accelerate. Press A to leap off. bar Jump (鉄棒ジャンプ) -- Latch on to any horizontal bar and Sonic will begin cutting gymnastic flips. A red indicator will appear at the apex of the flip: press A when you see the indicator to have Sonic let go and soar into the air. Light Dash (ライトダッシュ) -- The Light Shoes are required to perform this maneuver. Approach a trail of Rings and tap B or X to zip off at light speed along the chain. Light Attack (ライトアタック) -- The Taiko no Hikari item is required to perform this maneuver. Rev up with a Spin Dash near a group of enemies to charge up with light. When Sonic says "ready", release to bombard the enemies with a series of light speed Spin Attacks. Bound Attack (バウンドアタック) -- The Bounce Bracelet is required to perform this maneuver. Jump, then tap B or X while in midair to zip straight back down and rebound like a blue basketball. Chain the maneuver to add height to the reverb. Magic Hand (マジックハンド) -- The Magic Glove item is required to perform this maneuver. Approach an enemy, then use the Y button to toggle the action commands until you see "Magic Hand". With the maneuver highlighted, press B or X to reduce the enemy before you to a tiny sphere that may be disposed of at your leisure.

:: Shadow the Hedgehog ------------------------------------------------- Spin Attack (スピンアタック) -- Tap button A to leap into the air with a spin attack. The height of the jump is proportional to how long you hold the button down. Homing Attack (ホーミングアタック) -- Jump, then press the A button again while in midair to home in on the nearest enemy or Item Box. Somersault (サマーソルト) -- Tap B or X to roll forward with a brief somersault attack that can be used to smash wooden Containers or squeeze through tight gaps. Pick up the Flame Ring item and the Somersault becomes the more powerful Fire Somersault which can destroy iron Containers. Spin Dash (スピンダッシュ) -- Press and hold B or X to have Shadow rev up with a stationary spin, then release to dash off with a rolling attack. Grind (グラインド) -- Leap onto any narrow surface (such as a banister) and Shadow will grind along the length of the rail. Use the control stick for balance and hold B to accelerate. Press A to leap off. bar Jump (鉄棒ジャンプ) -- Latch on to any horizontal bar and Shadow will begin cutting gymnastic flips. A red indicator will appear at the apex of the flip: press A when you see the indicator to have Shadow let go and soar into the air. Light Dash (ライトダッシュ) -- The Air Shoes are required to perform this maneuver. Approach a trail of Rings and tap B or X to zip off at light speed along the chain. Light Attack (ライトアタック) -- The Taiko no Hikari item is required to perform this maneuver. Rev up with a Spin Dash near a group of enemies to charge up with light. When Shadow gives the word, release to bombard the enemies with a series of light speed Spin Attacks.

Tails and Eggman carry on the late E-102's shooting/platforming game mechanic, which has been fine-tuned for an altogether smoother experience. Tails has added another transformation to the versatile Tornado: a heavily-armed combat walker mode called the Cyclone. Eggman, meanwhile, drives his trusty Egg Mobile which has also been upgraded with a walking attachment. Each mech has a health gauge that depletes upon sustaining damage: grab Rings to restore health to the meter. Lock-on to as many enemies as possible in each sweep to rack up points.

:: Miles "Tails" Prower ------------------------------------------------- jump -- Tap button A to leap into the air. The height of the jump is proportional to how long you hold the button down. Vulcan gun (バルカン砲) -- Tap B or X to fire a straightforward bullet that can be used to destroy enemies or smash wooden Containers. Use the Bazooka upgrade to destroy more powerful iron Containers. Propeller Punch (プロペラパンチ) -- Approach an enemy and tap B or X to bean the bot with the Cyclone's propeller. Lock-on (ロックオン) -- Press and hold B or X to unleash a target laser that automatically locks-on to any breakable object it comes in contact with. Lock-on Missile fire (ロックオンミサイル発射) -- When you've got enough lock-ons, let go of the action button and Tails will cut loose with a barrage of homing missiles. Hovering (ホバーリング) -- The Booster is required to perform this maneuver. Jump, then press A in midair to fire up a booster jet and descend at a slower speed.

:: Dr. Eggman ------------------------------------------------- jump -- Tap button A to leap into the air. The height of the jump is proportional to how long you hold the button down. Vulcan gun (バルカン砲) -- Tap B or X to fire a straightforward bullet that can be used to destroy enemies or smash wooden Containers. Use the Taihou (cannon) upgrade to destroy more powerful iron Containers. Punch (パンチ) -- Approach an enemy and tap B or X to bean the bot with a giant punching glove. Lock-on (ロックオン) -- Press and hold B or X to unleash a target laser that automatically locks-on to any breakable object it comes in contact with. Lock-on Missile fire (ロックオンミサイル発射) -- When you've got enough lock-ons, let go of the action button and Eggman will cut loose with a barrage of homing missiles. Hovering (ホバーリング) -- The Jet Engine is required to perform this maneuver. Jump, then press A in midair to fire up a booster jet and descend at a slower speed.

Series stalwart Knuckles and newcomer Rouge must locate 3 Master Emerald shards in each Action Stage. Look at floating monitors to get a hint as to the whereabouts of each shard: you can only use 3 hints per piece, but an on-screen radar flashes and beeps with increasing regularity as shards are approached. Earn A ranks by finding the shards as quickly as possible without using hints.

:: Knuckles the Echidna ------------------------------------------------- Spin Attack (スピンアタック) -- Tap button A to leap into the air with a spin attack. The height of the jump is proportional to how long you hold the button down. glide (滑空) -- Jump, then press and hold button A while in midair to have Knuckles fan out his dreads for a gliding attack. Release to fall back down to terra firma. climb (壁登り) -- Jump onto any vertical surface to have Knuckles latch on. Maneuver him around the surface with the control stick and jump to let go. swim (泳ぎ) -- When submerged, press B or X to dive and A to surface. Maneuver with the control stick. Punch (パンチ) -- Tap button B or X to have Knuckles throw a powerful punch adequate for destroying wooden Containers. Tap twice in rapid succession for a quick follow-up jab and 3 times to finish off with a Spiral Upper. The Hammer Glove item allows Knuckles to destroy iron Containers. Spiral Upper (スパイラルアッパー) -- Rotate the control stick in a complete circle, then finish off by tapping button B or X. Knuckles will jet straight upward with a whirling uppercut. Drill Claw (ドリルクロー) -- Jump, then tap B or X while in midair to zip back down with a whirling knuckle attack. If you've got the Shovel Claw, Knuckles will dig into the ground upon making contact. dig (穴掘り) -- The Shovel Claw is required to perform this maneuver. While standing on the ground or hanging onto a wall, toggle the action menu until "dig" appears, then press B or X to burrow into the dirt and potentially unearth an Emerald shard or Item Box.

:: Rouge the Bat ------------------------------------------------- Spin Attack (スピンアタック) -- Tap button A to leap into the air with a spin attack. The height of the jump is proportional to how long you hold the button down. glide (滑空) -- Jump, then press and hold button A while in midair to have Rouge spread her wings for a gliding attack. Release to fall back down to terra firma. climb (壁登り) -- Jump onto any vertical surface to have Rouge latch on. Maneuver her around the surface with the control stick and jump to let go. swim (泳ぎ) -- When submerged, press B or X to dive and A to surface. Maneuver with the control stick. Kick (キック) -- Tap button B or X to have Rouge unleash a powerful kick adequate for destroying wooden Containers. Tap twice in rapid succession for a quick follow-up boot and 3 times to finish off with a vertical flurry of kicks. The Iron Boots allow Rouge to destroy iron Containers. Screw Kick (スクリューキック) -- Rotate the control stick in a complete circle, then finish off by tapping button B or X. Rouge will jet straight upward with a whirling kick attack. Drill Drive (ドリルドライブ) -- Jump, then tap B or X while in midair to zip back down with a whirling heel attack. If you've got the Pick Nails, Rouge will dig into the ground upon making contact. dig (穴掘り) -- The Pick Nails are required to perform this maneuver. While standing on the ground or hanging onto a wall, toggle the action menu until "dig" appears, then press B or X to burrow into the dirt and potentially unearth an Emerald shard or Item Box.

   The list of items and power-ups grows ever richer (read: excessive).

   Eggman's fauna-inspired robot army has taken a distant backseat to the comparatively dull GUN armada. GUN mechs drop Chaos Drives upon defeat while Eggman's robots leave behind the customary prancing animals.

   The scenario mode consists of a record 29 separate Action Stages: 6 as Sonic, 4 as Shadow, 4 as Tails, 5 as Eggman, 5 as Knuckles, 4 as Rouge, and 1 with all the above. Additionally, there are a substantial 18 boss fights and 2 Kart Race minigames. Each stage sports 5 unique Missions, though only the first must be cleared to proceed. Your performance is graded on a scale of A-E, with A being the best and E being a big, fat "no TV this weekend."

   There are 2 scenarios to play: Hero (starring Sonic, Tails, and Knuckles) and Dark (starring Eggman, Shadow, and Rouge). Clear both modes to unlock "Last", the conclusion to the story. (Big the Cat makes cameo appearances in the background of nearly every stage - his girth makes him a bit easier to spot than Waldo.)

   Pick up a Chao Key in any Action Stage then reach the goal to be warped to the Chao World, a hub that connects the 3 Chao Gardens. Once the Chao World has been accessed, it can be reached any time via the stage select menu.

Chao World -- Though no longer relevant to the story, Sonic Adventure's gelatinous darlings return with a heavily fortified virtual pet minigame. Like the first time, Chao raising is an inconsequential diversion: the story mode can be cleared without ever setting foot in the Chao World, but 10 Emblems await avid breeders and completionists. For the Chao basics, refer to the Sonic Adventure 1 page - this synopsis only covers new features. In addition to the original 4 traits (speed, power, fly, and swim), Chao now sport 3 all-new stats: luck, intelligence, and stamina. If your Chao is a lucky dog, he's less likely to trip during a race. If he's got brains, he'll solve puzzles faster and more accurately. The higher his stamina, the farther he'll be able to slog through a race without slowing down. These new stats can't be raised with the animal/Drive method: you'll need to pick up rare fruit in the Osanpo Adventure 2 VM game (see below). Additionally, the Chao's appearance is affected by the characters used to raise each specimen. A Chao brought up by any combination of the Hero characters (Sonic, Tails, and Knuckles) will turn white and develop a halo. Likewise, specimens raised primarily by the Dark side (Eggman, Shadow, and Rouge) will turn black and sprout devil tails. Chao raised in equal parts by both sides will remain blue and neutral. Unlike traits, a Chao's affinity does not affect its stats, only its physical appearance. Stat-fortifying furries can be obtained from Eggman's mechs, but those are scarce: most animals can be found prancing aimlessly around Action Stages or coaxed from hiding with a whistle. Chaos Drives can be obtained in abundance from GUN mechs: unlike animals, Drives won't reduce any stats, but they only fortify a single trait and are less desirable in general. Special animals don't lower any stats and are the Chao fuel of choice, but such specimens are rare (usually only 1 to a stage) and difficult to find. Normal animals: Swim penguin seal sea otter Fly peacock parrot condor Run rabbit cheetah boar Power bear tiger gorilla Special animals: Normal (Balance) skunk sheep raccoon Ghost half fish bone dog bat Rare dragon unicorn phoenix At the outset, only the basic Chao Garden is accessible from the hub. The Hero and Dark Gardens can be unlocked by successfully raising Hero and Dark Chao. Take a Chao of any affinity to the Kindergarten to garner some information about its strengths and maybe teach it a useless trick or two: Principal's room -- Talk to the head Chao honcho for a primer on Chao farming. Health Center -- Talk to the Chao doctor for a brief overview of your Chao's current condition as well as his strengths and weaknesses. Classroom -- Drop your Chao off at school to have it learn one of 16 cute albeit useless abilities (sing, dance, draw, etc.). BBS -- Examine the bulletin board to be whisked away to the SA2 Dricas website. Each of the 3 Gardens contains an Osanpo Machine: shuttle the Chao of your choice into a VM memory card to access Osanpo Adventure 2, a simple minigame even more primitive than its forebear. Sit and watch as your Chao encounters various events on his little excursion: occasionally you'll be asked to make a decision that affects the Chao's bearing. Make the right choices and steer your fluid friend down the path of happiness to be rewarded with a rare seed. Recurring events include: treasure chests -- Choose one of 3 switches to open the chest. Flick the right one and you'll earn one of 10 different power-up fruits along with a luck bonus of 100 (pick the wrong switch and your luck decreases). heart fruit (aphrodisiac) Chao fruit (raises all stats) Hero fruit (raises Hero affinity) Dark fruit (raises Dark affinity) smart fruit (raises intelligence) energy fruit (makes your Chao more active) carefree fruit (sedative) circle fruit triangle fruit square fruit battles -- A one-on-one fist fight between your Chao and a rival. Press the A button to stop the roulette on the light square and land a Guru-guru Punch. Lose the battle and your opponent will make off with any items you're carrying. goal -- Reach the goal to be rewarded with a rare seed. Take the seed to a Garden and give it to any Chao who's won the shovel and water pail items from the trial Races: the pint-sized agriculturalist will plant the seed, which eventually sprouts into a tree that bears rare fruit. Each Garden can contain up to 6 of these special trees, though they eventually wither and die. Nobi-nobi (normal) Puku-puku (normal) Mori-mori (normal) Paku-paku (Hero) Mogu-mogu (Hero) Ao-ao (Hero) Zara-zara (Dark) Kera-kera (Dark) Mera-mera (Dark) Press A at any time during the stroll to bring up the Osanpo Adventure 2 menu: status -- View your Chao's stats. snack -- Feed your Chao or toss unwanted items. pet -- Give your Chao a pat on the head. scold -- Scold your Chao. It hurts you more than it hurts him, maybe. item -- Check your item stash and discard excess baggage. Slot Machine -- You begin the game with 100 points: press up or down on the D-pad to place your bet (1 is the minimum). Press A to start the machine and tap once to stop each column. Line up 3 fruits in a row to win the fruit in question. When your points reach 0, the game ends. hello -- Connect your VM to a friend's and your pets will waste no time making sweet, sweet Chao love. Assuming your Chao are full-grown, each one will be heading home with an egg in tow. owner -- Displays your personal data (name, age, sex, birthday, blood type, favorite thing, personal secret). friends -- Displays data exchanged during "hello" meetings. settings -- Options include: name your Chao, enable/disable data exchange, and sound on/off. Any of your prize Chao may be put to the test in the Chao Races, accessible from the neutral Garden. New to the mix is the stamina bar: as the race wears on, your Chao's stamina slowly depletes. When the meter hits empty, your wonder water becomes exhausted and slows to a crawl, almost inevitably assuring failure. Cheer your diminutive warrior on with the L and R triggers, but note that the ensuing burst of enthusiasm will lop a healthy chunk off the stamina bar. There are 6 different circuits to enter: trial -- This beginner circuit consists of 4 courses each with 3 levels of difficulty. crab pond: test of swimming ability. Clear level 1 to win a shovel. stump valley: test of flying ability. Clear level 1 to win a water pail. mushroom forest: test of running ability. Clear level 1 to win a toy wand. block crag: test of power. Clear level 1 to win a toy car. Jewel Race -- This circuit consists of 6 courses each with 5 difficulty levels. Only the first 4 are available at the outset: clear all 5 levels of each course to open up the Onyx and Diamond races. Aquamarine: test of swimming ability. Clear all 5 levels to win a Sonic doll and an aquamarine medal. Topaz: test of flying ability. Clear all 5 levels to win a broom and a topaz medal. Peridot: test of running ability. Clear all 5 levels to win a book and a peridot medal. Garnet: test of power. Clear all 5 levels to win a pogo stick and a garnet medal. Onyx: test of intelligence & luck. Clear all 5 levels to win crayons and an onyx medal. Diamond: test of all abilities. Clear all 5 levels to win a bubble blower and a diamond medal. Challenge Race -- This circuit only opens after the initial 4 Jewel Races have been cleared. The Challenge Races consist of 12 courses against unique (and difficult) opponents: gold & silver, Chakuron, Omochao, animals, cockroach Chao, unhatched Chao, skull Chao, pumpkin Chao, ghost Chao, Chakuron again, rainbow Chao, and a Chaos Chao. Clear the animal course to win a ball; clear the pumpkin course to win a jack-in-the-box; clear the Chaos challenge to win a TV set and gold medal. Hero Race -- This circuit only opens after the initial 4 Jewel Races have been cleared and the Hero Garden opened. Only Hero and neutral Chao may enter (all opponents are Dark Chao). The circuit consists of 4 challenge-style courses: devil babies, devil children, skull troop, and devil vs angel. Clear the devil children course to win the Hero ball; clear the devil vs angel course to win a rocking horse and Hero medal. Dark Race -- This circuit only opens after the initial 4 Jewel Races have been cleared and the Dark Garden opened. Only Dark and neutral Chao may enter (all opponents are Hero Chao). The circuit consists of 4 challenge-style courses: angel babies, angel children, winged angels, and angel vs devil. Clear the angel children course to win the Dark ball; clear the angel vs devil course to win a radio and Dark medal. everybody race -- Pit up to 8 of your own Chao against each other. If you've got a favorite Chao from Sonic Adventure 1 that you just can't bear to part with, you can have your blue baby shuttled into one of the Sonic Adventure 2 Gardens, but be warned: his stats will be reduced to 0 and he will no longer be usable in the original game. If you've got enough Emblems, rare jewel eggs can be downloaded via the online black market: black (no Emblem requirement), silver (5 Emblems), gold (10 Emblems), ruby (20 Emblems), sapphire (20 Emblems), amethyst (20 Emblems), Emerald (20 Emblems) and the pockmarked Moon Chao (30 Emblems).

   In addition to the Story mode, there's the usual selection of diversions accessible from the main menu. A Stage Select allows free perusal of any Action Stage and Mission cleared in the scenario game (including the Chao World). The cantankerous Omochao provides an in-depth Tutorial for those who can't be bothered with instruction manuals. The options menu includes an exhaustive sound test, language setting (dialogue in Japanese or English with subtitles in Japanese, English, French, Spanish, or German), and the ability to disable Puru-Puru Pack feedback. Players may also hop directly to the Kart Race or Boss mode minigames.

   Kart Race opens after clearing Route 101 or Route 280 in Story mode. All 6 characters can play, each with their own vehicles and unique strengths. There are 3 in-game courses (Beginner, Standard, and Expert) and 3 download courses available through the website (High Speed Trial, Fantasy Zone, and Eggrobo Toujou!). The object is to be the first racer to complete 3 laps around each track. (See the Route 101 synopsis above for a breakdown of the controls.) Boss attack is an endurance game in which all of the story mode bosses are played in succession. Choose Hero Side, Dark Side, or All.

   If you've got a friend handy and a spare controller, you might dabble in the 2 player mode which consists of 3 different versus games: Action, Kart Race, or Chao Race. Kart Race is simply a one-on-one match in any of the 6 Kart courses while Chao Race is a 2-8 player match with Chao from any connected VM memory cards. Action is a split-screen race or brawl between opposing characters of the Hero/Dark persuasions. Collect Rings to perform special attacks that hinder your opponent. Clear all of a character's Action Stages in the scenario game to unlock a secondary outfit for versus mode and ace all of the stages to unlock a hidden replacement character.

• Sonic / Shadow -- Race to the Goal Ring in Green Forest, Radical Highway, or Sky Rail. Sonic's secondary costume is a yellow & orange HUmar outfit from Phantasy Star Online; Amy Rose is the secret character. Shadow's secondary costume is a red & gray HUcast outfit from PSO; Metal Sonic is the secret character.

  Rings	Sonic	Shadow	special action
  20	Speed Up	Speed Up	A momentary speed boost.
  40	Sonic Wind	Chaos Spear	A long-distance slash attack that inflicts damage on your opponent.
  60	Time Stop	Chaos Control	Freeze your opponent in place for 10 seconds.

• Knuckles / Rouge -- Race to locate 2 of the 3 Emerald shards in Wild Canyon, Pumpkin Hill, or Meteor Herd. Hints are shared by both players, regardless of who inspects the info monitors. Knuckles' secondary costume is a gothic-looking black & white ensemble; Tikal is the secret character. Rouge's secondary costume is a rather kinky masked dominatrix outfit that makes her look like a Go Nagai reject; Chaos Zero is the secret character.

  Rings	Knuckles	Rouge	special action
  20	Hammer Punch	Hip Drop	A long-distance tremor attack that can knock your opponent off balance.
  40	Thunder Arrow	Black Wave	A slash attack that leaves your opponent dizzy for a short period of time.
  60	Power Flash	Charm Ray	Freeze your opponent in place for 10 seconds.

• Tails / Eggman -- Blast the living snot out of your opponent in small arenas from Mission Street, Sand Ocean, and Weapons Bed. Tails' secondary costume is a red version of the Cyclone (same color scheme as the old Tornado 1); the secret character is a Chao piloting a Chao-shaped walker. Eggman's secondary costume is a camouflage version of the Egg Mobile; the secret character is Big the Cat piloting the Egg Mobile.

  Rings	Tails	Eggman	special action
  20	Laser Missile	Laser Missile	Nail your opponent with a flurry of lock-on missiles.
  40	Rocket Launcher	Rocket Launcher	Nail your opponent with a shower of homing missiles.
  60	Power Laser	Power Laser	Nail your opponent with a giant laser blast.

   The final option in the main menu is the Home Page button: click it to be whisked away to the official game website. From the website, players can access bonus downloads, an online strategy guide, a primitive BBS, and an online Chao Garden for swapping the fiendish liquid gremlins.

• Sonic Theme File: Available at release on 06/23/01. Sonic graphics and voice clips in the options menu. 2 blocks.
• High Speed Trial: Released 07/13/01. A new oval track for the Kart Race minigame. Sonic drives a high-end experimental car that can travel at the speed of sound. 81 blocks.
• Knuckles Theme File: Released 07/19/01. Knuckles graphics and voice clips in the options menu. 2 blocks.
• Tails Theme File: Released 07/27/01. Tails graphics and voice clips in the options menu. 2 blocks.
• Fantasy Zone: Released 08/16/01. A new Opa-Opa shaped Kart Race track. Omochao drives a unique Opa-Opa Kart. 61 blocks.
• Rouge Theme File: Released 08/24/01. Rouge graphics and voice clips in the options menu. 2 blocks.
• Eggman Theme File: Released 09/07/01. Eggman graphics and voice clips in the options menu. 2 blocks.
• Eggrobo Toujou!: Released 09/21/01. A new E-shaped Kart Race track inspired by a fan request. Eggrobo, peon robot from Sonic & Knuckles and Sonic R, acts as both driver and vehicle. 55 blocks.
• Halloween Theme File: Released 10/11/01. New Halloween-themed costumes for versus mode. Sonic dons a jack-o-lantern on his cranium and a pumpkin on his thorax; Shadow and Knuckles sport skeleton body paint; Tails' Cyclone gets a new orange & yellow paint job; Eggman's Egg Mobile gets a pumpkin coat; Rouge dons a towering witch hat. 2 blocks.
• Christmas Theme File: Released 11/30/01. New Christmas-themed costumes for versus mode. Sonic sports a red & white Santa jacket; Shadow favors the sleeveless Santa vest look; Tails' Cyclone and Eggman's Egg Mobile both get red & white peppermint paint jobs; Knuckles decorates his dreads with green stripes and bells; Rouge slips on a red & white boot/glove ensemble and paints her wings to match.

• Visuals are richer and smoother. Draw-in distance has been rolled back considerably and there's more graphic activity going on in general: extra pick-up objects, new textures and lighting effects, more background structures, etc. White Jungle sports rain effects rather than the drab fog of the DC version while the PSO Ver.2 billboard in the Big Foot arena now advertises PSO Episode I&II.
• The game features a progressive scan (480p) mode for compatible TV's.
• Certain rough pockets of level design have been tweaked for better flow (such as the long stairway halfway through City Escape).
• The Emerald radar in Knuckles/Rouge stages has an extra level of sensitivity: when you're within spitting distance of the hidden shard, a red exclamation point will appear over your character's head.
• A few of the 180 Emblems have been redistributed: there are now only 9 to be earned through Chao farming, 4 of which have been shifted from racing to Chao Karate. The missing Emblem has been slapped onto Cannon's Core: ace all 5 Missions to procure it. (Fortunately, A rank criteria for Cannon's Core is much more forgiving than in the ruthless DC version.)
• All Rings on-hand at the end of each Action Stage are saved in a tally used to purchase items from the Chao black market.
• All online functions have been removed along, mysteriously, with all Big the Cat cameos...

   Rival players may also settle their vendettas in Chao Racing, Chao Karate, or Kart Racing. The Kart Race sports 3 tracks (Beginner, Standard, and Expert) along with 6 playable characters (Sonic, Tails, Knuckles, Shadow, Eggman, and Rouge). Each character has an extra kart that can be unlocked by opening every story mode mission for the hero or antihero in question. (Sonic's alternate vehicle is the prototype car from the Dreamcast High Speed Trial while Rouge's is Eggrobo. Sadly, the download tracks themselves are missing in action.)

   Further augmentation has transpired in the realm of Chao ranching, making this the most extensive virtual pet operation in the entire Sonic series:

Hidden menu theme: (GameCube version only) To access a hidden menu theme featuring the President's secretary (of all people), open the theme select menu and rotate the control stick about 30 times.

   While brainstorming ideas for the game, Takashi Iizuka and the other designers looked to their new surroundings for inspiration. The hilly Capital city is modelled after San Francisco right down to the Golden Gate bridge. Sonic's new showcase ability - grinding - is derived from a West Coast street sport that was new and popular at the time. The spiny hipster even sports Soap shoes, a brand of footwear with concave arches specifically designed for handrail grinding.

   The first screenshots were unveiled to the public in September 2000 as part of an online promotional event. A fully playable demo of the first stage, City Escape, was included with all initial shipments of Phantasy Star Online (released December 21, 2000). The game itself was released worldwide on June 23, 2001 - the 10th anniversary of Sonic's debut title. A full-blown "10th birthday" campaign was devised to mark the event, including a limited edition Birthday Pack version of the game. The Birthday Pack includes the game itself accompanied by an unassuming blue box containing a commemorative coin, small pamphlet of Sonic history, and a music CD with select tracks from Sonic 1, 2, 3, Sonic CD, Sonic & Knuckles, Sonic R, and Sonic Adventure. The pack was intended as a limited edition item to be sold for only 2 days in Japan (the 23rd and 24th) and distributed only with pre-ordered copies of the game in the US and Europe; however, the bundle was overproduced and languishing stock can still be purchased from many distributors for dirt cheap. As a result, the "limited edition" Birthday Pack has no collector's value to speak of.

Got Ring? The walls in City Escape sport a number of spoof ads, most references to Sonic's own world (Chao in Space on DVD, Chaos Soda, etc), but among the posters is a "Got Ring?" series, which lampoons the California Milk Processing Board's famous "got milk?" campaign. The joke may be lost on non-American players.

J.D. Bernal: Tails describes the ARK as the "first Bernal sphere space colony." Dr. John Desmond Bernal (May 10, 1901 - September 15, 1971), an Irish-born physicist, proposed in 1929 a theoretical space habitat built into a hollow spherical shell. Known as the Bernal Sphere, the design has served as the basis for a number of speculative space habitats.

• Yuji Naka appears as an extra in the Japanese TV commercial for Sonic Adventure 2.
• Issue #98 (June 2001) of the Archie comic book features a cover story loosely based on Sonic Adventure 2.