Sonic Adventure 2

"Maria...this is what you wanted, right? This is my promise I made to you..."

- Shadow's final words before falling to Earth.

Sonic Adventure 2 (ソニックアドベンチャー2) is a platform game developed by Sonic Team and published by Sega in 2001 as a part of the Sonic the Hedgehog series. It is the sequel to Sonic Adventure.

Sonic Adventure 2 was released worldwide on 23 June 2001. In Japan, it also came with a limited-time Birthday Pack (バースデイパック) during the first two days of release to mark the 10th anniversary of the release of the original Sonic the Hedgehog. This game introduces two new playable characters, Shadow the Hedgehog and Rouge the Bat and is also one of the few Sonic games to feature Dr. Eggman as a playable character. On 10 December 2001, a port of the game called Sonic Adventure 2 Battle was released for the Nintendo GameCube in Japan, followed by North America on 11 February 2002 and Europe on 3 May 2002. It was announced at Sonic Boom 2012 that the game was being re-released on Xbox Live Arcade and PlayStation Network in Fall 2012. It was also released on Microsoft Windows on 19 November 2012.

Single player
Gameplay takes place between two different points of view storylines, the "Hero" story and the "Dark" story; the player has the option of advancing in either one or the other at any time. The "Hero" story features Sonic, Knuckles, Tails and the non-playable Amy, while the "Dark" story features Shadow, Rouge and Doctor Eggman. Each hero character plays similarly to their respective dark character and vice versa. Levels advance in order for each storyline, come between each of the playable characters.

Levels featuring Sonic or Shadow are designed in much the same way as they were in Sonic's levels in Sonic Adventure, where the player's primary objective is simply to get to the end of the level. Levels with Tails or Dr. Eggman allow the player to control a mechanized robot walker and generally blast their way to the end, much like E-102 Gamma's stages in Sonic Adventure. Knuckles and Rouge are required to scour their levels for shards of the Master Emerald (with the exception of 2 stages where they must find keys into Eggman's base and 1 stage where Chaos Emeralds are located), again, much like Sonic Adventure. Interspersed between the levels are various bosses, which one particular character must fight. The main story line can only be finished when both "Hero" and "Dark" story modes are finished, and an extra story feature is revealed where the player must use all the characters to beat it.

Within Action Stages, players collect rings and defeat enemies, with a timer counting the time spent within the level. At the end of each stage, the player is given a score based on the number or rings collected and time spent within the level. The less time is used and the more rings obtained, the higher the score is. The player is also given a rank-based performance, a letter grade that is either A, B, C, D, or E, with A being the highest and E being the lowest. Irrelevant to any other factors, an A Rank is automatically awarded to players that complete any score-ranked mission with all of the rings from that level in the player's possession.

There are five missions within each Action Stage; in order to obtain the second mission, the player must complete the first one, to unlock the third, the second mission must be finished, and so on. In order from first through fifth, the missions are to complete the level, collect 100 rings, find a "lost Chao" using the Mystic Melody upgrade, finish within a time limit, and complete a "Hard mode" version of the Action Stage.

Emblems are also given within the game; there are 180 Emblems in total. In order to gain all 180 Emblems, players must defeat every mission within every stage, achieve an A rank in all stages and missions, etc. After collecting all 180 Emblems, the player unlocks an extra level 3-D Green Hill level, a remake of Green Hill Zone from the original Sonic the Hedgehog game.

Two-Player Mode
Unlike its predecessor, Sonic Adventure 2 has a two-player mode. Like the single player mode, 2P Player has action racing (Sonic/Shadow levels), treasure hunting (Knuckles/Rouge levels) and shooting (Tails/Dr. Eggman levels). Each type of stage is played split-screen except for the shooting stages. The conditions for winning in each type are as follows: There is also a Kart Racing mini-game in the two-player mode, but the player will have to clear the Kart Stages in the Hero and Dark stories in order to enable Kart Racing in 2P Play.
 * Action Race - The player who reaches the Goal Ring first wins.
 * Treasure Hunt - The first player to find two pieces of the Master Emerald wins.
 * Shooting - The first player to reduce their opponent's health gauge to zero wins.

In the two-player mode of the GameCube port, Sonic Adventure 2: Battle, along with action racing, treasure hunting, shooting, and Kart Racing, there's also Chao Racing, Chao Karate and a random mode that chooses the characters and stages for you.

Along with the six main characters of the game, the two-player mode has some unlockable characters that are exclusive to 2P Play. In the Dreamcast version, these include: Amy Rose (playable after beating all of Sonic's levels with an "A" rank), Metal Sonic (playable after beating all of Shadow's levels with an "A" rank), Tikal (playable after beating all of Knuckles' levels with an "A" rank), Chaos 0 (playable after beating all of Rouge's levels with an "A" rank), a Chao (playable after beating all of Tails' levels with an "A" rank), and Big (playable after beating all of Eggman's levels with an "A" rank). In the GameCube version, all of these characters are already playable, though Big is replaced by a Dark Chao.

Another exclusive to the two-player mode is alternate costumes. In the Dreamcast version, the player could unlock special costumes for each of the six main characters by completing all of their respective missions. These costumes originated from Phantasy Star Online, an online RPG series that was also developed by Sonic Team. Also on the Dreamcast version were seasonal costumes for Halloween and Christmas, only available when playing two-player mode on 31 October (Halloween costumes) and Christmas Day (Christmas costumes). The GameCube port also has alternate costumes, which are different from the Dreamcast version and can be obtained after clearing all of a character's missions with an "A" rank.

Levels

 * 1) City Escape - Sonic - 1P / 2P (called "Downtown Race" in 2P) (Contains Magic Gloves - requires Bounce Bracelet/Flame Ring)
 * 2) Radical Highway - Shadow - 1P / 2P (Contains Flame Ring - requires Air Shoes)
 * 3) Mission Street - Tails - 1P / 2P (Contains Booster)
 * 4) Route 101 (Kart) - Tails - 1P / 2P (Kart Racing Mode is based on this level)
 * 5) Route 280 (Kart) - Rouge - 1P / 2P (Kart Racing Mode is based on this level)
 * 6) Aquatic Mine - Knuckles - 1P Only (called "Pool Quest" in 2P) (Contains Air Necklace)
 * 7) Green Forest - Sonic - 1P / 2P (Contains Ancient Light)
 * 8) White Jungle - Shadow - 1P / 2P (Contains Air Shoes)
 * 9) Iron Gate - Eggman - 1P / 2P (Contains Laser Blaster - requires Large Cannon)
 * 10) Security Hall - Rouge - 1P / 2P (Contains Treasure Scope - requires Mystic Melody/Iron Boots)
 * 11) Prison Lane - Tails - 1P Only (Contains Laser Blaster - requires Bazooka)
 * 12) Metal Harbor - Sonic - 1P / 2P (Contains Light Shoes)
 * 13) Weapons Bed - Eggman - 1P / 2P (called "Deck Race" in 2P) (Contains Large Cannon)
 * 14) Pumpkin Hill - Knuckles - 1P / 2P (Contains Shovel Claw)
 * 15) Sky Rail - Shadow - 1P / 2P (Contains Ancient Light)
 * 16) Wild Canyon - Knuckles - 1P / 2P (Contains Mystic Melody - requires Shovel Claw)
 * 17) Dry Lagoon - Rouge - 1P / 2P (Contains Mystic Melody - requires Pick Nails)
 * 18) Sand Ocean - Eggman - 1P / 2P (Contains Mystic Melody - requires Jet Engine)
 * 19) Hidden Base - Tails - 1P / 2P (called "Pyramid Race" in 2P) (Contains Mystic Melody - requires Bazooka)
 * 20) Pyramid Cave - Sonic - 1P Only (called "Grind Race" in 2P) (Contains Bounce Bracelet)
 * 21) Egg Quarters - Rouge - 1P / 2P (Contains Pick Nails)
 * 22) Death Chamber - Knuckles - 1P / 2P (Contains Hammer Gloves)
 * 23) Meteor Herd - Knuckles - 1P / 2P (Contains Sunglasses - requires Hammer Gloves)
 * 24) Mad Space - Rouge - 1P / 2P (called "Planet Quest" in 2P) (Contains Iron Boots)
 * 25) Cosmic Wall - Eggman - 1P / 2P (Contains Protective Armor)
 * 26) Lost Colony - Eggman - 1P / 2P (Contains Jet Engine)
 * 27) Eternal Engine - Tails - 1P / 2P (Contains Bazooka)
 * 28) Crazy Gadget - Sonic - 1P Only (Contains Flame Ring)
 * 29) Final Rush - Sonic - 1P / 2P (Contains Mystic Melody)
 * 30) Final Chase - Shadow - 1P / 2P (Contains Mystic Melody)
 * 31) Cannon's Core - all playable 1P characters (except Shadow) - 1P Only
 * 32) Green Hill Zone (unlockable stage) - Sonic - 1P Only

Hero

 * 1) Bigfoot (after City Escape) - Sonic
 * 2) VS. Eggman (before Prison Lane) - Tails
 * 3) VS. Shadow (before Green Forest) - Sonic
 * 4) King Boom Boo (after Death Chamber) - Knuckles
 * 5) Egg Golem - (before Eternal Engine) Sonic
 * 6) VS. Rouge (after Meteor Herd) - Knuckles
 * 7) VS. Eggman (aboard the Space Colony ARK) (after Crazy Gadget) - Tails
 * 8) VS. Shadow (aboard the Space Colony ARK) (after Final Rush) - Sonic

Dark

 * 1) Hot Shot (after Iron Gate) - Shadow
 * 2) VS. Tails (after Weapons Bed) - Eggman
 * 3) Flying Dog (after Security Hall) - Rouge
 * 4) VS. Sonic (after White Jungle) - Shadow
 * 5) Egg Golem (after Sky Rail) - Eggman
 * 6) VS. Knuckles (after Mad Space) - Rouge
 * 7) VS. Tails (aboard the Space Colony ARK) (after Cosmic Wall) - Eggman
 * 8) VS. Sonic (aboard the Space Colony ARK) (after Final Chase) - Shadow

Last

 * 1) Biolizard (after Cannon's Core) - Shadow
 * 2) Finalhazard - Super Sonic and Super Shadow

Reception
Opinions of Sonic Adventure 2 are variable among both professional reviewers and fans of the Sonic series. At its initial release on the Dreamcast, Sonic Adventure 2 was the recipient of very positive reviews, averaging an 89% according to critic compiler Metacritic. However, the Nintendo GameCube port (Sonic Adventure 2 Battle) fared considerably worse in terms of reviews, despite having no single player gameplay changes from the Dreamcast version and only an 8-month gap between their releases.

To date, the game has done well with sales of 1.44 million units in North America alone, making it one of the GameCube's highest selling games and it is still one of the most popular GameCube games. This game also made it to Player's Choice.

Hero Story
This story begins with a military helicopter (Sigma-Alpha 2) flying over the city with Sonic being captured aboard it. Suddenly the pilot starts shouting "What?! The hedgehog is gone! He's taking out everyone aboard!" At that moment, Sonic the Hedgehog jumps out of the helicopter, rips off a piece of the wing to use as a snowboard, and then jumps off. After he destroys a military mecha, he encounters a near look-alike of himself named Shadow the Hedgehog who has stolen a Chaos Emerald from the bank a while earlier. Sonic realizes that the military is mistaking him for Shadow. Shadow proceeds to use the emerald to transport to a different location, and Sonic is arrested.

At the same time, Knuckles the Echidna and a mysterious character named Rouge the Bat are fighting over who owns the Master Emerald. Dr. Eggman tries to steal the Master Emerald, but Knuckles stops him in his path by breaking the Master Emerald into pieces. Knuckles and Rouge have a hunt for the pieces of the Master Emerald. Knuckles finds the first three pieces in Wild Canyon.

The next day Miles "Tails" Prower comes to Prison Island in search of Sonic, rescuing Amy Rose from Dr. Eggman in the process. Then Amy frees Sonic from his cell, and Sonic escapes on a missile. Knuckles leaves Wild Canyon, and heads for Pumpkin Hill. There he finds three more pieces of the Master Emerald. Knuckles leaves Pumpkin Hill, and heads for the Aquatic Mine. Meanwhile, Sonic gets weary, jumps off the missile, and lands on a small island in a vast jungle. There he confronts Shadow once again.

He soon discovers the jungle is going to explode and leaves just in time. When they get back, Eggman is on televisions everywhere and it is revealed he is being taped from a space-station named "Space Colony, ARK". Suddenly half of ARK comes off, revealing a long pointer called the 'Eclipse Cannon' which shoots out a powerful beam and destroys half of the moon. A timer on screen appears saying 24 hours until mass destruction. Later, Tails discovers Space Colony ARK and the massive power of the Eclipse Cannon. He has to find Sonic, tell the President and escape the military all before it is too late. He eventually finds Sonic and escapes the military.

Meanwhile, Knuckles finds the last three pieces he can find of the Master Emerald in the Aquatic Mine. He later pops out of a manhole beside Tails, who is talking to Sonic and Amy over a phone on loudspeaker. Tails chases down the President, then he and Sonic tell the President about the situation they are in. Sonic, Knuckles, Tails, and Amy then head for Dr. Eggman's "secret" base inside the pyramid. Sonic breaks through the security system. Knuckles then has to find three keys to get into the rocket room. Knuckles defeats King Boom Boo, the king of ghosts. After that, Dr. Eggman appears and summons the Egg Golem, which Sonic has to take care of. As soon as he is defeated, they blast off in the rocket.

In all the excitement of the space ship, the cargo bay opens releasing the pieces of the Master Emerald Knuckles had collected. Sonic remarks that only the Master Emerald pieces were inside there. Knuckles thinking quickly takes control of the ship causing it to spin out of control. Knuckles jumps ship and lands on a small planet and finds the pieces he lost, leaving Sonic, Tails, and Amy screaming on the ship which then crash lands into the ARK. He defeats Rouge and gets the rest of the Emerald. Meanwhile, in Space Colony ARK, Tails is heading for the engine of the Eclipse Cannon. He destroys the engine, so it's up to Sonic now. Amy gets kidnapped by Eggman and demands the last emerald in exchange. Sonic, who has a fake chaos emerald, makes it to the central control room. Unfortunately for Sonic, Eggman anticipated the likelihood that one of them had the fake emerald, and after tricking Tails into admitting that Sonic had the fake emerald, Eggman then shot Sonic out of an escape capsule that was going to explode in the middle of space. Before being launched out, Sonic encourages Tails to stop Eggman, and tells Amy to take care of herself. Just before the pod exploded, Sonic also considered the possibility of using the fake Chaos Emerald to escape via Chaos Control, due to it having similar wavelengths to an actual Chaos Emerald.

All Tails, Amy and Eggman can see is a capsule blowing up, so they presume Sonic was killed in the vincinity. Tails is so riled up that, in a burst of anger, he defeats the Doctor. Meanwhile, Knuckles (with the full Master Emerald) spots Sonic coming out of a portal. Sonic tells Knuckles how he used Chaos Control to save himself, and speeds to the Eclipse Cannon. Sonic confronts Shadow one last time, and destroys the Eclipse Cannon. Tails, grieving over Sonic's "death", briefly and half-heartedly attempted to tell Sonic that he managed to defeat Eggman. Sonic, having apparently overheard Tails' comment, responds by congratulating him, causing Tails and Amy to learn that Sonic survived. Sonic then told them to look outside. They then look out the window and sees Sonic at the tip of the cannon smiling.

Dark Story
This story begins with Dr. Eggman infiltrating Prison Island in search of the Ultimate Life Form A.K.A. Project: Shadow, a weapon created by his grandfather, Gerald Robotnik. He finds the "weapon" inside a capsule and by using a Chaos Emerald (and the password M.A.R.I.A.), he soon discovers that the weapon is a male hedgehog. The doctor initially mistakes Shadow the Hedgehog for his enemy Sonic the Hedgehog, and nearly fights him. Then, Shadow proves himself by defeating the military guard fighter. After Shadow defeats him, he leaves, heading for Space Colony ARK and tells Eggman to bring more Chaos Emeralds and meet him on the ARK.

Meanwhile, Rouge the Bat is fighting with Knuckles over who truly owns the Master Emerald. Dr. Eggman uses this to his advantage, and attempts to take the Master Emerald. Knuckles stops him by breaking the Master Emerald into pieces. Rouge and Knuckles have to hunt for the pieces of the Master Emerald. Rouge finds three pieces in the Dry Lagoon.

Later, Dr. Eggman goes to his base to check up on things, and watch the replay of the news. He finds out that the G.U.N. robots are guarding his pyramid base. He destroys them and goes on inside. While he is watching the replay of the news, he discovers that Shadow had stolen a Chaos Emerald from the Federal Reserve Bank yesterday with everyone mistaking him for Sonic. The scene changes to where Shadow is leaving the bank when he has a flashback of what happened on Space Colony ARK with him and his friend Maria Robotnik. He proceeds to speed down the highway, destroying any robot that gets in his way.

He later sees Sonic, explains to Sonic who he is and leaves. The next day, Rouge decides to infiltrate Dr. Eggman's base. To do so, she has to find three keys. Meanwhile, Dr. Eggman and Shadow are on board the ARK. Shadow tells Eggman about Space Colony ARK and the power of the Eclipse Cannon. He then puts in the two Chaos Emeralds. They return to the base at the time Rouge finds the last key. Rouge persuades her conditions to Eggman into helping her by giving him a Chaos Emerald, and telling him where three other emeralds were. Before the deal is closed, she introduces herself to Shadow.

Shadow, Dr. Eggman, and Rouge headed for Prison Island, where the three Chaos Emeralds are. Dr. Eggman breaks through the security system and defeats Tails, who happens to be there. Rouge finds the three Chaos Emeralds and defeats another Military Fighter. However, the fight leaves her locked inside the room. Shadow rushes through the jungle, plants the bomb, finds Sonic and fights him. It ends in a tie, neither of them win because Shadow has to escape the jungle before it blows up. So he grabs Rouge, and warps onto the ARK.

Later, Eggman is broadcasted on the televisions everywhere and it is revealed to all he is being taped from the ARK. Half of the station comes off, which reveals a long pointer called the Eclipse Cannon which shoots out a powerful beam, destroying half of the moon. Then, there is a timer on the screen saying 24 hours until mass destruction. At the ARK, Rouge explains that she knows where the location of the last Chaos Emerald is, with Tails. Shadow and Rouge try to catch the Tornado (Tails' plane). Rouge can't catch up in her car and Shadow can't catch them in Sky Rail. They head back to the ARK to tell Eggman.

By this time, Knuckles has unlocked the entrance to Eggman's base, so Eggman summons his Egg Golem. However, Sonic damages the head of the golem, causing it to turn on Eggman. Eggman has to destroy his Egg Golem to pass. A while later, he and Shadow (who are still on the pyramid) discovers that Sonic and his friends are on the ARK. Rouge soon discovers that Knuckles is on a small planet with the pieces of the Master Emerald. She finds half of the pieces, then they fight. It is a draw and she gives the pieces to Knuckles.

Meanwhile, Eggman has kidnapped Amy Rose. A while later, Eggman discovers Tails and Sonic rushes into the room he was in. Eggman shoots Sonic out of an escape capsule which is going to explode, then he defeats Tails, despite the young fox's best efforts and takes the real emerald. Meanwhile, Shadow witnesses Rouge attempting to take the other six Emeralds and exposes her as a government agent. Rouge then proceeds to show him the results of Project Shadow, with the picture showing an entirely different being. She then asks Shadow that if the picture shows the real Ultimate Life Form, then she wonders who or what is standing in front of her. Eggman contacts Shadow, declaring that someone is attempting to get to the Eclipse Cannon and orders him to stop them before the cannon fires again. Shadow finds it to be none other than Sonic, who he fights and defeats one last time. Meanwhile, Eggman is putting in the last Chaos Emerald. While he is cheering over his apparent victory, a nearby monitor turns on forebodingly.

Last Story
It continues from the Dark Story where the cannon screen is flashing frantically. Eggman is puzzled and does not know what to do but then he sees his grandfather, Gerald Robotnik, tied to a chair on the screen of the cannon.

Meanwhile, it continues from the Hero Story, where Sonic and Knuckles enter the room Amy and Tails are in, but, then, they hear a rattle and suddenly Rouge comes out of the blue. "You, you haven't give up yet?" Knuckles says. Rouge says that they are all doomed because the Space Colony ARK is heading towards Earth at a tremendous velocity. On televisions everywhere, including the ARK, Gerald Robotnik is tied to a seat, explaining how the ARK will crash into Earth and destroy it along with the savage humans, with the power of all seven Chaos Emeralds.

Eggman comes in and Knuckles starts yelling at him, thinking that Eggman is behind all of this. But then Eggman gives Rouge his grandfather's diary and Rouge reads it out loud, revealing that the professor went insane after his granddaughter Maria was killed. When the Space Colony ARK was shut down, Maria was killed in the process. Gerald went mad because he loved Maria so much. He wanted to curse all humans, so he made the Eclipse Cannon and when having enough power, ergo the 7 Chaos Emeralds, would be programmed to make ARK fall to Earth. It is revealed that Gerald made Shadow to benefit mankind, but Space Colony ARK was destroyed and as a result, so was project Ultimate Life Form A.K.A. Shadow. He was able to complete his research and finish Shadow and he says that "you may awaken it if you wish to fill the world with destruction.".

Sonic, Tails, Knuckles, Rouge and Eggman has to stop the energy from the Chaos Emeralds to stop Space Colony ARK from crashing with Earth. They then have a plan to stop the Chaos Emeralds with the Master Emerald. Meanwhile, Amy finds Shadow and convinces him to help save the world. Though Shadow was reluctant initially, he then receives a flashback of Maria telling him the same as her dying words. He then takes off saying "I have to go now! I need to keep my promise to Maria...and you.".

Sonic and Knuckles are seen at a shrine that looks somewhat like the shrine of the Chaos Emeralds, with the Chaos Emeralds there. When Sonic and Knuckles try to get closer to the shrine to stop the Chaos Emeralds with the Master Emerald, Gerald's voice is heard again and a snake/lizard like beast called the Biolizard is awakened. They realize that this is the prototype of the Ultimate Life Form. Shadow appears and distracts the Biolizard, while Sonic and Knuckles get to the shrine and find a space for the Master Emerald. Knuckles does the chant to negate the power of the Chaos Emeralds and the Biolizard disappears after engaging a fight with Shaodw. They hear Eggman's voice saying that the Biolizard is still alive as it used Chaos Control to teleport and fuse together with Space Colony ARK to become the Finalhazard and is keeping it on its crash course to Earth.

Space Colony ARK is no longer being powered by the Chaos Emeralds, but now by the Finalhazard. Sonic and Shadow use the Chaos Emeralds to transform into Super Sonic and Super Shadow, respectively. They fight the Finalhazard in outer space and just as they are about to stop Space Colony ARK, Maria's voice rings in Shadow's head again about giving people a chance to be happy. Both Sonic and Shadow used a super-powered Chaos Control to warp the crashing space colony ARK back to its normal place, but Shadow's power is drained and he falls to Earth, realizing that he has fulfilled Maria's request in his "dying" moments. Sonic returns to the ARK alone, giving Rouge Shadow's ring cuff and everyone reflects on the events that have transpired, wondering what they will do next as the credits roll. As Sonic leaves to return to Earth, he quietly says farewell to Shadow the Hedgehog in the same manner as Maria.

Sonic Adventure 2 and Sonic Adventure differences
For Sonic and Shadow, instead of jumping on a capsule, the end of a stage is cleared when jumping into a giant ring with the word "GOAL" flashing in the middle. Adventure fields do not return in Sonic Adventure 2, but alternate stories come back. This game, though, does not have alternate stories for each character, and three characters are in one story, a lot like Sonic Heroes. There is a 2 Player mode, unlike Sonic Adventure. When treasure hunting, the radar telling the player how close he/she is to the emerald no longer has the color blue as "closer but still not close enough." Tails does not roam around any more without a mechanical system, and always is in the Tornado in its walking-robot mode. Although when roaming around Chao World, both Eggman and Tails run around without their walking robots, and Tails can fly around again, without getting tired. A new action was added to Sonic and Shadow, the Somersault. The music to the Power Sneakers and Invincibility are the same musical writing, but with different instruments.

Biolizard
Biolizard, the Prototype of the Ultimate Life, is a creature which appears as the second to last, and final, boss; it is also seen briefly in a flashback in Shadow the Hedgehog. The Biolizard appears as a giant and alien-looking lizard with a life support system on its back with tubes running down its neck to its head. According to Sonic X, the Biolizard is 85 meters long, 30 meters wide, 19.5 meters tall and weighs 87.5 tons. The massive creature can either attack by trying to bite its enemies with crushing jaws, or attempting to hit them with its tail. Biolizard can also generate large black orbs from its mouth, create smaller, but extremely numerous, pink egg-like orbs that it can shoot at a target and manipulate gravity. Additionally, as a product of Project Shadow, the creature can use Chaos Control.

The Biolizard was an earlier version of "Project Shadow", a government project run by Professor Gerald Robotnik that was intended to create an "Ultimate Lifeform" as a first step towards humanity discovering the secret of immortality. Due to the experiments, it later needed a life support system. While the Biolizard was successful in the way that it was could regenerate and restore itself, and could self-reproduce, it was also unruly and dangerous. It was locked away when Gerald, with the aid of the alien Black Doom, produced a more advanced being: Shadow the Hedgehog. The military, on Earth, began to worry and fear about what Robotnik was building on the ARK. When GUN raided Space Colony ARK in order to put a stop to Professor Gerald's plans, they found the Biolizard and captured it. It didn't go down without a fight, however and it killed almost all of the GUN soldiers.

The Biolizard remained encapsulated aboard the ARK until Doctor Eggman placed the seven Chaos Emeralds into the Eclipse Cannon. This initiated a hidden program by Gerald, that would use the Emeralds to power the ARK into a doomsday causing collision with the planet below. The program released the Biolizard to defend the Armageddon plan from tampering by the combined forces of Eggman, Sonic the Hedgehog and friends. But Amy Rose had convinced Shadow to help save the Earth, and he engaged and defeated the giant reptile in battle by damaging its Life Support System. Knuckles rushed in afterwards and used the Master Emerald to negate the power of the Chaos Emeralds, supposedly putting a halt to the collision course. However, the Biolizard then used Chaos Control to teleport outside and fuse with the space station itself, becoming the Finalhazard. Its body mounted on the eclipse cannon, it continued the rush towards Earth by pulling it there itself. As Finalhazard it attacks with the pink orbs and firing out energy beams from its damaged Life Support System. It was, however, weakened by the loss of its Life Support System, revealing slight weak points on its body and was killed by the combined power of Sonic and Shadow in their super forms. Together, Sonic and Shadow then used Chaos Control to place the ARK back into orbit, ending the collision course and saving the planet.

King Boom Boo
King Boom Boo is the king of all ghosts. He has ghost powers, but he and his ghost minions can lose power because of the sun. If they are touched by the sun's light, they become weaker and open to attacks. When they're not in contact with sun light, they become stronger and gain powers. His powers include throwing plasma balls, shooting a plasma beam from his mouth and turning into a shadow in an attempt to avoid getting hit by Knuckles. He will also attempt to bite the player at close range. He was defeated by Knuckles at Death Chamber. His name (and to some extent, his appearance) are reminiscent of Nintendo's King Boo.

He appears on an episode of the anime series Sonic X, haunting an old mansion with his minions. However, he doesn't appear in Sonic X's adaptation of Sonic Adventure 2.

Egg Golem
The Egg Golem is a boss character appearing in Sonic Adventure 2. After Knuckles the Echidna defeats King Boom Boo, Eggman appears and summons a giant animated statue called the Egg Golem to battle Sonic. To defeat the Egg Golem, Sonic must run to his back, jump across the platforms that stick out, and attack the Golem's control mechanism atop its head.

In the Dark Story, Sonic immediately jumps up and kicks the control mechanism, causing the Egg Golem to go haywire and attack Eggman. In order to defeat it, Eggman has to use his Volkan Cannon to destroy its internal power generators. Once all three of them are destroyed, the Egg Golem becomes disabled and sinks down into the quicksand.

According to an eyecatcher card from Sonic X, the Egg Golem is 57 metres tall and weighs 250 tons Egg Golem information card from Sonic X. The Egg Golem fights by smashing its hands and head against the circular platform that Sonic or Eggman are standing on. It can also create an electrical field around itself to repel attacks, or spin its arms around itself to sweep enemies off the platform.

The Egg Golem also appeared in the Sonic X adaption of Sonic Adventure 2. It was remotely controlled by Bokkun who used it to fight Sonic and Knuckles. The two heroes had a hard time with the golem, but eventually Cream the Rabbit stole the remote control from Bokkun just after he took Agent Topaz hostage, and made the Egg Golem chase Bokkun into the desert. It later appeared standing on top of Doctor Eggman's pyramid during Super Sonic and Super Shadow's fight against the Finalhazard, with Bokkun standing on its head.

A similar character was also used in the game Sonic & Knuckles as the first act boss in the Sandopolis Zone. Like the Egg Golem it was an animated statue, vulnerable only on its head, and although it was not named, it may have been a partial inspiration for the later character. It is also unknown if it was recycled from the scrapped Egg Golem-type boss in Sonic X-Treme.

Sonic Adventure 2: Battle
Sonic Adventure 2: Battle is the enhanced port for GameCube.

Version differences

 * A Black Market has been added to the Chao Kindergarten. It was originally a limited feature of the website.
 * Big the Cat's cameos have been removed from the stages, oftentimes with a ring. He is also replaced by a Dark Chao in the multiplayer mode. However, he can still be seen in cutscenes, but only on Dark Side and Final Story.
 * Amy Rose, Chao Walker, Tikal, Metal Sonic, Dark Chao Walker and Chaos 0 are now available at the start of the multiplayer mode and have their own movesets. The characters were originally only selectable between "Hero" and "Dark", and bonus characters performed exactly like their 1P counterparts with no unique voices. The 2P Mode also has more stages and settings, and alternate costumes now give the character slightly different attributes.
 * The unlockable costumes for Sonic, Shadow, Knuckles, Rouge, and Eggman have changed somewhat.
 * Tails and Eggman's lock-on power now utilizes a faster system able to lock-on every 8 frames which was previously every 12 frames on the Dreamcast.
 * The first frame of Knuckles' Spiral Upper attack, and Rouge's Screw Kick, has roughly double the reach on Dreamcast. This was removed in the GameCube version, leaving it with only the same reach as the rest of the move. Additionally, a few more objects were given immunity to those moves, most notably the safes around the perimeter of Security Hall.
 * Treasure hunting has an additional level of detection - an exclamation point in a red action bubble will appear above a character's head once they are right within reach of the emerald or key.
 * Chao Karate has been added to the Chao Stadium. The A-Life system has also been slightly enhanced, with all-around more accessible options.
 * The VMU game Chao Adventure 2 has been replaced by the Tiny Chao Garden, available via GBA connection.
 * Omochao no longer welcomes the player to Chao World.
 * There is more music in the GameCube version. For example, the Dreamcast's Chao World theme was moved to the new Chao cave selection, and in its place is the Chao Racing menu theme from Sonic Adventure.
 * Some of the game's graphics have been tweaked. The main characters have minor enhancements, but secondary characters and enemy models have been slightly downgraded. Inexplicably, some of the writing on the mechs has vanished as well.
 * For example, in the Dreamcast version, many of the G.U.N. robots have blue fiery jets to keep them floating/moving; in the GameCube version, however, all that's left are the jet nozzles. In terms of side-characters, Amy's teeth are no longer prominent and Maria Robotnik's eyelashes were removed.
 * Also in levels where lighting would pulse down the screen like in Egg Quarters, when you encounter the Egg Beetles, and Iron Gate when a security sector has been breached, the lights no longer pulse. Lighting in general (as well as shading and textures) were also adjusted, with some areas receiving more clarity and others being simplified.
 * There are also some different visual effects altogether - for example, White Jungle did not originally have rain and instead had purple spores floating down. Graphical glitches were also reduced.
 * Some of the level layouts and ranking requirements were adjusted for better flow.
 * The intro is different showing the six main characters instead of just showing outer space with the game's logo.
 * The title screen and the main menu screen are different and reorganized.
 * Some posters in the stages have been changed or rearranged.
 * The Hero and Dark Gardens were a little bit bigger in Dreamcast version. The Dark Garden in particular had a larger body of the blood-red water and the cave, as well as a ramp leading up to another tombstone in the original release.
 * The Dreamcast version had the "Download Event" mode where the player could download various events, although to a far smaller scale than Sonic Adventure. Some features exclusive to the Dreamcast version include a Halloween and Christmas theme for the character outfits in 2P mode, as well as three additional race tracks. Features brought back to the GameCube release include a selectable Eggrobo racer and expanded character themes for the menus (which was noticeably missing Shadow).
 * The Knuckles segment of the final level, Cannon's Core, is made easier due to boxes being placed in the areas where he gets air bubbles. When Knuckles takes in an air bubble he sinks a few inches. In the original version, taking in air would make him sink and touch the hazardous ground and take damage or lose a life. Because of the boxes in the GameCube version, Knuckles can take in the air bubbles without getting hurt.
 * Some of the cutscenes have been altered slightly, either with camera angles or dialogue timing. One noticeable instance is the first encounter between Knuckles and Rouge - she has a different camera angle when she looks up at Eggman, and she screams at a different time when the Master Emerald is broken (overlapping Eggman's quiet exclamation). Her mouth just gapes open with no sound coming out.
 * In the scene when Sonic jumps off the helicopter, he is now seen with his Soap shoes. In the Dreamcast release, he is briefly seen with his original shoes before switching them off-screen. The angles and lens flare are also different.
 * In the GameCube version of the cutscene where Sonic and Shadow meet for the first time, the officers' voices are cut off short and over lap each other. In the Dreamcast version of the cutscene, the officers shout at Sonic in full sentences.
 * When the President is speaking to Eggman, there seems to be a lag issue between their conversation on Eggman's screen showing several arm movements at one time.
 * Right after Pyramid Cave, the Eggman symbols at the end of the level do not appear in the following cutscene.
 * The cutscene where Rouge and Shadow meet up for the last time had a few changes such as shifting from Rouge's theme to Maria's theme.
 * The song "Deeper" for the Death Chamber level removed the Sonic and Knuckles conversation lyrics and replaced it with a saxophone solo. The reason for this was most likely because Sonic says at the final lyric of the "conversation" "Ya damn right, Knuckles!"
 * Japanese language settings are set as the default in the Japanese region, which was not the case in the Dreamcast version (similar to Sonic Adventure International).

PlayStation 3/Xbox 360 port

 * The game has been remastered in 16:9 HD using the GameCube version's assets (some of the cutscenes remain in their original 4:3 SD format).
 * Almost all of Big the Cat's cameos return in the port, except for his appearance in Wild Canyon due to a programming oversight.
 * "Battle Mode" DLC - This downloadable content features the following:
 * The opening and title screen is changed to "Sonic Adventure 2 Battle"
 * Adds Chao Karate game in single player and multiplayer
 * Automatically adds Amy, Metal Sonic, Tikal, Chaos 0, Chao Walker, and Dark Chao Walker to the two-player character roster.
 * Adds several stages to multiplayer that were only available in Sonic Adventure 2 Battle.
 * Adds the "Theme" item in the Options Menu.
 * The game itself costs $10.00/£6.49, while the DLC costs $3.00/£1.79.
 * All of the billboards with Soap advertising on them have been removed and replaced with other Sonic Team billboard assets (this is most likely due to licensing issues).
 * However, they have not been removed altogether - on the PC version, if the player removes the objtex_stg13.pak file from the PRS folder where the game is saved, the Soap advertisements are restored.
 * Some of the character's life count sprites have been changed. For example, Sonic's sprite resembles the side view of him compared to the original icon.
 * There was an error when you selected the game on XBLA, so for the first day of release, many people were not able to download the game or the trial; this could be circumvented by logging onto Xbox.com and selecting the game's downloads from its page.
 * Omochao appears in the loading screen giving hints and tips (a Sonic Generations model of Omochao is used). This only occurs in the Xbox 360 and PC version; the PlayStation 3 port skips that screen.
 * The cross on the Health Packs has replaced with the Letter "H".
 * The GBA in the Chao Garden that was used to transfer Chao has been changed to a machine shaped like a Chao's head, with the only function to release Chao. This is similar to the PC port of Sonic Adventure DX.
 * The XBLA version has a few more glitches, one of which concerns the Hero Garden. If a Chao is fed a fruit from a Hero Garden tree, every time the fruit shrinks, it will raise the Chao's Stamina Stat up 2 to 3 bars instead of the usual 1. This can be used to raise the Stamina Stat very quickly. However, it only applies to the fruit from the trees; taking a fruit in from elsewhere (such as a Chao Fruit from the Black Market) will raise Stamina normally. Other glitches include activating the test level and errors in widescreen cutscenes.

Advertisement
The Dreamcast version is known for its infamous commercial which shows a scientist approaching a hedgehog labeled "Good Hedgehog" and petting it. The camera then goes to a tank labeled "Bad Hedgehog" where a cow is being lowered in. Eating sounds could be heard along with screams from the cow until the screen goes back to the bad hedgehog burping (this is a parody of a scene from Jurassic Park). The GameCube version's advertisement shows several real life hedgehogs being trained to take on the roles of Sonic and Shadow in the game.

Soundtracks
Three original soundtracks were released for Sonic Adventure 2: the vocal album called Sonic Adventure 2 Vocal Collection: Cuts Unleashed; the score called Multi-Dimensional Sonic Adventure 2 Original Sound Track; and, in North America, the Sonic Adventure 2 Official Soundtrack. Additionally, one of the major theme songs of this soundtrack made it into Sonic and the Black Knight.

Trivia

 * In the "Good Hedgehog, Evil Hedgehog" TV commercial, the "Evil Hedgehog" section is a spoof of Jurassic Park, as the "Evil Hedgehog" ate the cow as it was lowered, similiar to how the Velociraptor ate the cow in Jurassic Park.
 * Among the XBLA Sonic games, this game so far has the most amount of gamerscore given when unlocking all of the achievements (500G in total).
 * This is the first Sonic game to have swearing in the English track. Swear words can be heard in the lyrics of the main theme of Knuckles the Echidna and in the lyrics for the background music of some of the stages he goes through (i.e., "Deeper"). This was also the main reason why the Gamecube version has a "Lyrics" warning on the ESRB rating.
 * In the game, Eggman blows up half of the moon, but in later games with cutscenes in outer space scenes, most notably Shadow the Hedgehog and Sonic Colors, it is still perfectly intact. In Colors, it is actually shot again. Also, the Earth does not appear to have any gravitational stress by the destruction of half of the moon. However, as recently confirmed by Ilzuka Takashi of Sonic Team at Sonic Boom 2013, in all later games after Sonic Adventure 2, the Moon is actually still blown up. However, from Sonic Heroes onwards, you are just looking at the opposite side of the Moon, the part that Eggman blew up is on the opposite side of the world, so, if you went across the world you'd see the destroyed section of the moon.
 * Sonic Adventure 2 is the only game where Sonic wears Soap shoes in order to promote the product and the new extreme sport, freestyle grinding, that the shoes were made for. There are also many billboards, blimps and benches in the game that advertised the shoes. Sonic himself wore a custom version of the Scorcher/Nitro Soap Shoe, while Shadow wears a pair of custom Broadside Soap shoes, as grinding (or "soaping") debuted as an important new gameplay element. Also for some reason, Sonic uses shoes similar to the soap shoes in one of the episodes of season 3 for Sonic X - in that episode, Chris launches a capsule with the shoes to Sonic, who then proceeds to grind on a vine.
 * This is the first non spin-off game where Dr. Eggman is playable.
 * Ever since grinding has been introduced in Sonic Adventure 2, almost every Sonic game after it has grinding as a core gameplay element as well. Additional characters like Tails, Knuckles, and Rouge who couldn't grind in this game learned how to later. Everyone also learned to grind with their normal shoes as Soap Shoes are never used again.
 * This is the first game in which Eggman points a gun at someone.
 * This is one of the few Sonic games where Sonic doesn't fight Dr. Eggman directly.
 * In the cutscene mentioned above, the pilot of the helicopter identifies himself in military talk as "Sigma-Alpha 2", which translates from Greek as "SA2," the game's initials.
 * When using Sonic's bounce attack, if the player pauses the game and removes the pause menu with X and Y he or she can see Sonic's normal red shoes in his slightly blurry ball animation.
 * Shadow was originally deemed dead after the events of the Last Story, but his reception from fans caused him to return to the series.
 * This is the last main series Sonic game on a Sega console since Sega eventually withdrew from the console market after the release of this game.
 * There is some unused dialogue in the game, including some Omochao quotes.
 * Some of the deleted clips were brought back in the GameCube (Battle) version, however, as an easter egg if Sonic or Shadow carries Omochao to the goal ring.
 * If one were to go to the Theme Select in the Options menu and rotate the Control Stick clockwise for a few moments until hearing a chime sound, they would then see a picture of the President's Secretary and should then be able to select the Secretary's theme.
 * Green Hill Zone returns as an unlockable stage, which marks its big comeback in recent Sonic games, as it had not been seen for several years. Also, the stage's background music is a remixed version of the original song, and when Sonic destroys an enemy (which are the first Badniks instead of G.U.N. robots), the same sound effects from the original game are played instead of the usual sound effects.
 * In the GameCube version, when pausing, pressing and holding the Y and X buttons at the Pause Menu will make it disappear, giving the player a clear view of the screen.
 * In the Mad Space level for Rouge, there are two easter eggs. First, go under the starting platform to its base, and kick open the iron box where you will find a blue defense item container from the Dreamcast game Phantasy Star Online: Episode I &amp; II. Also, go to the outlying platform with a circle of rings and two iron boxes. Kick open the nearest iron box and you will see a green medical/technique item container from the same aforementioned RPG.
 * In the Chao Garden, there's a glitch that makes it possible to reuse an animal or a Chaos Drive from the Action Stages multiple times on a single chao. While holding your animal, go as close to your Chao as possible without giving it the animal. Then simply drop the animal in front of your Chao and, if done correctly, the Chao will not only do the level up animation, but its stats will go up as if you actually handed the animal to the Chao, only now you can pick the animal up again. This can also be done with Chaos Drives and can be used to quickly raise your Chao's stats.
 * Also in the Chao Garden, one of the shows shown on the garden's little TV (achieved by winning all Challenge Races), features a big, mustached, orange cat (Robotnik) chasing a speedy, little blue mouse (Sonic). This is a spoof of the classic cartoon show, Tom &amp; Jerry.
 * It is believed that Tails, Rouge and Shadow were not originally planned to be playable, due to the face that they did not make a significant appearance in trailers until towards the end of production.
 * Shadow was originally going to be named "Terios" ('reflection of'), and Rouge was going to be "Nails" (in direct contrast to Knuckles). The prototype names can still be found within the game's (any versions') files.
 * In all versions, the in-game screenshots appearing in the Tutorial and Credits originate from the Dreamcast release. While some noticeable differences such as the different-colored select button, the treasure hunting exclamation point and the controller graphic were added, you can see there aren't any new GameCube screenshots due to some Dreamcast-only things appearing, such as the altered posters in the background of City Escape, the inscriptions on the mechs (most clearly the Eggman insignia and "IVO" on the back of the Egg Walker), and the ARK's screen at the end of Dark Story that reads "DANGER!! DANGER!!" rather than "WARNING!! WARNING!!" This is an oversight on the developers' part. A similar mistake occurred in Sonic Adventure DX, in which one of the buttons in one of the character instructions was that of the Dreamcast version rather than the GameCube one.
 * In the Chao Garden, some characters will say untranslated lines (mostly Tails and Eggman). Also, the chao in the Chao Kindergarten sing songs in Japanese.
 * In the original Dreamcast version of the game, if you insert the disk into a PC then special wallpapers will be available to download as an easter egg. As well as that, there is a list of main series Sonic Games prior to Sonic Adventure 2, although Sonic CD is absent from the list. It reads:
 * SERIES TITLE:


 * SONIC the Hedgehog, 1991


 * SONIC the Hedgehog 2, 1992


 * SONIC the Hedgehog 3, 1994


 * SONIC and KNUCKLES, 1994


 * SONIC JAM, 1997


 * SONIC Adventure (for Japan), 1998


 * SONIC Adventure, 1999


 * SONIC Adventure International, 1999


 * SONIC Adventure 2 The Trial, 2000.


 * The camera can be used to move objects in the game. This is most noticeable in the Chao Garden if you have a fruit in front of the camera and the player walks away from it. The same thing can be done in the Chao Garden in Sonic Adventure.
 * In the first cutscene of the demo version, before the player enters City Escape, the man on the radio says, "What the hell?" in the text which marks the first Sonic game to have swearing (although this is not in the final release of this game). In the final release, the script instead says, "What?!"
 * Some of the characters' theme songs are based on their Sonic Adventure songs, most notably Sonic and Tails', and Amy's theme song is exactly the same.
 * This game's port is the first Sonic game for a Nintendo home console.
 * Shadow has the least amount of stages out of all the characters, with only 4 (Radical Highway, Sky Rail, White Jungle, and Final Chase).
 * The "Chao in Space 2" movie billboard as well as the billboard advertising for the DVD Edition of "Chao in Space" in City Escape refers to the "Chao in Space" movie billboard near the entrance of Casinopolis in Sonic Adventure.
 * In Sonic Generations, Shadow is Sonic's rival. During the opening cutscene, it is a reference to the Sonic Adventure 2: Battle opening, and during the fight, a remix of For True Story plays and if Sonic grabs 2 or 3 power cores depending on the difficulty, Live and Learn plays for a brief time.
 * City Escape returns in the console versions of Sonic Generations, as the fifth level in the game, in the Dreamcast Era.
 * Radical Highway returns in the 3DS version of Sonic Generations. Oddly enough, Sonic has never been confirmed to have visited Radical Highway before Sonic Generations.
 * In the Hub World in Sonic Generations, when in the Egg Dragoon section of the hub, a remix of E.G.G.M.A.N plays.
 * Tails is the only playable character in Sonic Adventure 2 that does not fight a major boss.