Capsule

Capsules (カプセル), also known as Prison Eggs are large metal containment units created and used by Doctor Eggman to contain captive animals, presumably so that they can later be turned into badniks. First time seen in original 16-bit version of Sonic the Hedgehog, capsules have appeared in various shapes, but are most often a metal container with a single switch on the top. Pressing the switch will either destroy or open the Capsule, thereby releasing the prisoners.

Description
There are numerous, different capsule designs being featured in the franchise, which are all created by Doctor Eggman to imprison animals friends inside of them. There have been exceptions being including something else in capsules. It is described as large grey unit, that has small support pedestals beneath it. The common aspect seen in Eggman's mechanical creations (aside of badniks) is that, capsules do have yellow and black stripes set on them. On the top of it is usually seen the switch, that opens all loose hatches, while releasing all animals inside.

One capsule is generally featured at the end of single, second or third act of zone/action stage rather having signpost. By pressing the switch on top of it (or hitting the capsule at one time) releases hatches around the capsule, thus releasing animals out of it. The player usually finds it right near boss arena after defeating the boss of zone.

In recent games, starting from Sonic Adventure 2, Egg Capsules have been replaced by Goal Rings, though a different variation called Wisp Capsules appear in some levels of Sonic Colors, which Sonic must destroy to save the captured Wisps. Despite that, capsules have been featured in occasional times.

Sonic the Hedgehog (1991)
Capsules are first featured in original 16-bit version of Sonic the Hedgehog, as being seen at the end of the zones' third act, following a boss battle. These capsules are light grey, shapely units that have yellow and black stripes and an small window at the right front. It has four small support pedestals under it. At top of the capsule is grey switch. After pressing the switch, the capsule starts exploding while the player moves automatically after the doctor. After exploding, dozens of small animal friends are freed and quickly moving away in both directions, leaving behind a pile of remnants of the capsule and results starts popping out. Scrap Brain Zone act 3 doesn't feature a capsule, as the player is transferred to Final Zone automatically after completing it.

The 8-bit version of the game with same name also features Capsules (known as "Metal Cages" in the American manual) at the end of third act at each zone, which is short and only has a boss battle. Capsules are more thinner than their 16-bit counterparts, but does mostly have the same method, while the player moves to the next zone and animals run to the other direction. Only third act zones that don't have capsules in the end are Scrap Brain Zone and Sky Base Zone.

Sonic the Hedgehog 2
Capsules is next seen in 16-bit version of Sonic the Hedgehog 2, where a single capsule is now featured at the end of second act on each zone, after defeating one of Robotnik's vehicles. This capsule's design is similar to previous one, but it is more detailed. There are four hatches, black and yellow stripping on lower part and four support pedestals beneath it. There is yellow switch, which by pressing it opens hatches and releases animals inside of it. After doing that, the player is able to move at background while results are being calculated. Capsules are not featured at Sky Chase Zone, Wing Fortress Zone and Death Egg Zone, which only have one act.

Drastically different looking capsules (known as Egg Prisons in the American manual) are featured in 8-bit version of the game with the same name. These variations float in the air and are round-shaped, resembling Robotnik himself, as having eyes and mustaches. Instead of a switch, the player has to do Spin Jump onto it and the capsule will open its bottom hatch. Sonic moves to the next zone while capsule keeps exploding and all animals fall out the capsule and run away. Crystal Egg Zone don't feature capsules as featuring two different endings after completing boss from either of the zones.

Sonic CD
Capsules are next seen in Sonic CD, at third zone of the round while having slightly different design. These capsules are large units, which have bigger pillar and round pod at its top with black and yellow stripe and two small antennas. The color scheme and shading changes depending the level and its timeline. Instead of animals, these capsules contain seven flower seeds of Little Planet, which are also used to power up badniks in the game. After hitting capsule once after the boss, the player moves to the next round, while capsule is exploding and seven seeds land to the ground and increase flowers to the place. Capsule is not seen at Stardust Speedway (saving Amy Rose from being tied up to the pole) and Metallic Madness (ending the game after final boss).

Sonic Spinball
The Sonic the Hedgehog 2 variation of capsule is seen in Sonic the Hedgehog Spinball, as being part of third bonus stage called "The March". Here, the player has to destroy the capsule and free the animals, while dozens of chicken robots that resemble Scratch are walking around the capsule. The player has to enough of chicken robots to get hit the capsule.

Sonic the Hedgehog 3 & Knuckles
Capsules are seen repeating role in Sonic the Hedgehog 3 and its add-on continuation Sonic & Knuckles. After beating the boss, it is being featured at the end of second act on each zone. There are two variations of capsules. The first, standard one is similar to ones from Sonic the Hedgehog 2, although being more round-shaped. The second variation is similar to first one, but it is upside down and able to fly by using small rotors on support pedestals. Flying capsule variations are seen at Angel Island Zone, Marble Garden Zone, Launch Base Zone (With Sonic 3 alone, the game ends at this point) and Lava Reef Zone (Knuckles is not able to get this due having different route). Capsules are not seen at Hidden Palace Zone, Sky Sanctuary Zone and Death Egg Zone.

The Flying Battery Zone, Eggman's floating fortress contains numerous capsules throughout the zone and at the zone's background. Some do contain animal friends, but others contain rings, badniks, or nothing at all. In some cases, the switch on top of the capsule may act as a spring. Capsule at the end of the Zone's first act will turn into the act's sub-boss Gapsule, which has eyes and two large spiked balls. There is also single one left inside of the pyramid at second act of Sandopolis Zone, that by pressing the switch, releases Hyudoros around to harm the player, when the place is completely dark.

Sonic Adventure
Capsules make third dimensional appearance in Sonic Adventure, as these units appear at the end of some of Sonic and Tails' Action Stages. The capsule design is more simple, but bulky. It has yellow and black striping around, small foot supports and large releasing button on the top. Once the capsule is opened, the player has officially reached the end of the action stage and the scores are tallied. These capsules are also seen at action stages that aren't featured at first place, if the player has already beat the game.

Sonic Pocket Adventure
Capsules are normally seen in Sonic the Hedgehog Pocket Adventure, as being featured at the end of second act on each zone after beating the boss vehicle. In the game, capsules have taken the design from Sonic the Hedgehog 2. Capsules are not featured at Sky Chase, Aerobase Zone, Gigantic Angel, Last Utopia and Chaotic Space.

Sonic Advance games
Capsules are featured in Sonic Advance games, although having different design and featured different way at every game. In the first title, it repeats its role from the previous games, as after beating the boss, it is being featured at the end of second act on each zone. Capsule's simple design is hybrid of between Sonic the Hedgehog 2 and Sonic Adventure, but having now Eggman Empire logo on it. It comes crashing down at the end of every zone but the last 2, while the crashing doesn't hurt the player, only bouncing him back. Capsule is not featured at Egg Rocket Zone and Cosmic Angel Zone, which are only one act zones.

Sonic Advance 2 doesn't feature capsules generally, but Eggman used a round-shaped one to imprison Vanilla the Rabbit and several Flickies, while packing them to the capsule on the last machine. As the player defeats Eggman as Super Sonic at True Area 53, he tries to rescue Vanilla who is inside of capsule, that is overheats due to the immense amount of friction at atmosphere re-entry. After for a while, the capsule breaks open at the atmosphere, but Sonic still manages to save Vanilla just before they touch the ground while Flickies fly around them and giving support.

In Sonic Advance 3, there's one of two mini-games including a more larger capsule with more buttons, which must be pressed as quickly as possible within a time limit to earn a certain amount of points to open it. Depending on the time taken to complete this, the player is rewarded with extra lives.

Sonic Heroes
Different looking capsules are featured now as breakable objects in Sonic Heroes. These capsules can be found at Eggman's operation bases, such as Rail Canyon, Bullet Station, Egg Fleet and Final Fortress. These capsules are white and red colored, tube looking units with round glass dome at upper section. Any power type character in the game can destroy these capsules easily on the way. Like containers, some of them might hide item boxes as well. These are even featured as the main objective of Team Chaotix in their mission at Bullet Station: Destroy 30/50 capsules!

At the beginning of Team Dark story, Shadow is seen to being inside of capsule in a coma while getting found and released by Rouge the Bat. Only few moments later, E-123 Omega destroys the same capsule, but Shadow manages to dodge strike. In the climax of Team Dark's story, Rouge finds the corridor hall with many capsules containing Shadow Androids.

Sonic Rivals 2
In Sonic Rivals 2, the capsule is only featured on its own card, where its appearance is taken from Sonic Adventure. This card is able to collect by doing successfully Speed Boost 100 times in the game.

Sonic Chronicles: The Dark Brotherhood
In Sonic Chronicles: The Dark Brotherhood, lots of capsules can be found anywhere of Metropolis and many other locations. The design of capsules is mostly taken from Sonic the Hedgehog 2, but there are also simple variations, that loosely bears resemble to ones from Sonic Advance without Eggman Empire decal in it.

Sonic the Hedgehog 4
Capsules make a reappearance in both two episodes of Sonic the Hedgehog 4, as having its design directly taken from Sonic the Hedgehog 2. It can normally be found near right after the boss fight of each zone and by pressing the switch on top of the capsule, the zone ends. The capsules can be targeted with Homing Attack. Only zones that don't have capsules are E.G.G. Station Zone and Death Egg mk.II Zone.

Sonic Generations
Capsules also made a notable appearance in console versions of Sonic Generations, as being featured at two challenges on both Seaside Hill and Planet Wisp for classic Sonic. In the game, these capsules have its design from original Sonic the Hedgehog, with many detailed changes, including grey and cyan colored switch. In two missions, the player has to find and open capsules, that are located that at many places of two challenge levels.

There are more than ten capsules in each challenge and each single capsule contains 14 animal friends, as the challenge requires to release 140 animals. Challenges include many obstacles and badniks being on the player's way or surrounding capsules. As the player jumps onto the switch, it releases animal friends inside from capsule. The single capsule is also featured as trophy at secret trophy room of the game.

Sonic Lost World
In upcoming Sonic Lost World, capsules look loosely similar to ones from Sonic Genearations and do appear at the end of every zone, as the player has to reach capsule in order to complete the zone. As in Sonic the Hedgehog, the player must press the switch on top of the capsule to free the animal friends trapped inside. The player can also find other, smaller capsules hidden throughout zones in order to free more animal friends and increase the player's score. In the 3DS version of the game, Sonic can open a capsule by performing a homing attack on the button.

Eggman is also seen carrying a Capsule while Sonic and Tails are chasing him in the opening cutscene.

Wisp Capsules
Sonic Colors features different variants of capsules called Wisp Capsules created by Doctor Eggman, which keep Wisps imprisoned inside. There are three kinds of Wisp capsules: smaller ones, that the player is open and release the Wisp's power, medium sized ones that are featured at the end of certain acts (similar to capsules) rather than Goal Ring and bigger ones, that are only featured in cutscenes of the game.

Sonic the Hedgehog Story Comic
Capsule appears in Sonic the Hedgehog Story Comic Volume 2 as doctor Eggman succeeds in capturing the animals of South Island to one of capsules. After Ricky and Cucky gets freed by Sonic, they lead Sonic to the Star Land Zone where capsule is located. After beating Orbinaut and Eggman who had Eggmobile with a spike underneath, Sonic press the button on top of capsule and frees all animals of South Island.

Sonic the Hedgehog Yearbook 1991
The single capsule is featured in Sonic the Hedgehog Yearbook 1991' story "Double Sonic", where the design of it is taken from original Sonic the Hedgehog. When Sonic finds out his friends are once again captured, he runs through the Green Hill Zone after Flicky told him about Capsule. However the capsule turns out to be a trap, which exploded on his face and Robotnik tries to smash him with his wrecking ball connected to his Eggmobile until Tails comes out to help Sonic.

Sonic the Comic
In Fleetway's Sonic the Comic, these Prison Eggs are created by Doctor Robotnik, but only one is briefly seen in the beginning of issue 30's story "Metamorphia", where the Freedom Fighters destroy one of Robotnik's prison eggs and freeing citizens of Emerald Hill Zone at it.

Archie Comics
In recent issues of Archie's Sonic the Hedgehog comics, Doctor Eggman has started to use capsules to imprison Mobians, although Dark Egg Legion under Iron Queen's rule is seem to have a one capsule before. In issue 226, during the events of the Genesis arc, Sonic uses one of Newtrons to crash one of capsules that Snively has been listing. After Sonic defeats him, he also freed many forest animals from another capsule that Snively hasn't yet listed, which contained Sally Acorn, Antoine D'Coolette, and Boomer. Sonic then joined the Freedom Fighters in attempt to locate Eggman. After the Genesis arc., Eggman is seen to keep several capsules at storage areas inside of Death Egg Mark 2.

Eggman's new SWATbot models called Egg Swats lead by Mecha Sally, are seen capturing citizens of Furville and putting them to the capsules in issue 236. They are later freed from capsules by Sonic's own and new Team Fighters and thus citizens start defend themselves, while Eggman's troops retreat. In another time and another place, Doctor Eggman manages to capture all Sonic's friends to the single, large capsule by using traps and new models of Caterkillers in issue 242, during the Olympic games. Sonic aspects the challenge against Metal Sonic on Olympic sports. The last Olympic sport is a race to the capsule, which contains Sonic's friends. By the power of Olympic Spirit, Sonic got his strength and high speed back, easily wins the race and frees all his friends out of the capsule, while Metal Sonic crumbles on the ground.

Trivia

 * In Sonic the Hedgehog Story Comic Volume 2, "Clash!! South Island", the Egg Capsule is shown to possess retractable robotic arms that allow it to actually capture the animal friends itself.