Final Zone

The Final Zone is the seventh and last zone in the original 16-bit version of Sonic the Hedgehog. Final Zone is the shortest zone in the game, as it only features the final boss of the game, while having final fight against Dr. Robotnik inside his private laboratory.

Sonic must defeat Robotnik without getting hit, as there are no rings to protect Sonic, which makes it one of the most toughest bosses in the game. When the player starts at the beginning of the Final Zone, Sonic is already get up the final dungeon of the previous zone. The player has to move to the final room to start final battle against Doctor Robotnik, who uses four engine pistons to defend himself and crush the hedgehog.

Boss Guide
After arriving the laboratory room, Robotnik starts attacking by using four large engine pistons, which are clean steel with small yellow and black stripes on them. These pistons are able to crush Sonic easily into the ceiling or floor. Due a lack of rings, it also means instantly losing a life as well.

Every time two of four pistons come out; one decoy, and one with Robotnik laughing inside of it and the player must attack the piston with Robotnik in it. Each time the pistons move, the player is able to attack Robotnik once. However the player has to be careful depending which pistons will come out attempting to crush Sonic. Also between each piston cycle, there are also small electric generator creating four spark balls, that come from the ceiling towards Sonic, who must dodge them. When generator is creating and targeting these spark balls, the player has to choose place where to avoid them. The player can target them to the center of room and then do Spin Jump to dodge them completely. After this, another two pistons will appear and the battle keeps repeating the pattern after this.

Like every other bosses in the game, the player has to hit Robotnik eight times to finish off the doctor for good, while at the same time avoid other pistons and spark balls. After doing all eight hits, pistons start exploding slowly and Robotnik is seen escaping from the room. The player has to keep following him, as Robotnik is seen hopping on his Eggmobile (that is in its rare landing state) and starts flying away. During this, there are two choices, which the player is able to do, but don't greatly affected to the game. If the player lets Sonic do his finish move into Eggmobile, it starts exploding and be wrecked, while also falling slowly down to the bottomless pit at the end of zone. The player is also able to let him go as well.

After clearing Final Zone, the game progresses to the end sequence and credits. The ending sequence differs if the player has collected all of the Chaos Emeralds or not from Special Stages, which the player would be able to enter during the game.

Sonic X Comics
The Final Zone (mistakenly told to be Final Stage) is briefly featured in Archie Comics's Sonic X #11. After Sonic saved Cream, Cheese and Vanilla from the glass box, Cheese pressed the switch, that transported the whole gang to the Final Zone, where Eggman in one of pistons was waiting for them.

When the gang start to finish Eggman and his pistons, Eggman outside of the video game, had almost getting enough points to launch Sonic and his friends to the moon, who actually were trapped to the tower base. At the same time, Chris and Chuck managed to release Sonic and friends from the game, that and the game was powered by Master Emerald before the base tower got destroyed.

Archie Comics
The Final Zone is also featured in the Archie Comics's Sonic the Hedgehog #227 that takes place of "Genesis" arc. When Sonic, Sally and Rotor entered the depths of the Scrap Brain Zone, Sonic suddenly got a magic forcefield around him and Dr. Eggman showed up inside one of pistons. After talking, both of them started fighting against each other, until Sonic found himself caught in a dead end.

Before Eggman managed to crush Sonic, water suddenly started popping out above the piston where Eggman is in it with several pieces of Orbinauts from Labyrinth Zone, and Antoine (who before handed fell down to the endless hole at the Labyrinth Zone) found himself on Doctor's arms, and, at panic, he smacked Eggman to the face. This gave Sonic the chance to finish Eggman and his pistons for good. While Freedom Fighters tried to find Eggman, who was seen silently escaping in the background. Sonic noticed this and tried to catch him, but unsuccessfully. While he managed to hit him on his Eggmobile and made him crash, Sonic believed that this was not the end of the doctor.

Trivia

 * In the 2013 re-release of original Sonic the Hedgehog, Final Zone has only slight changes in normal in-game, as the doorway, where the player comes to the room, will be closed for the battle, as the tube at the other side of room will be solid until it brakes off after defeating the final boss. These changes have been made due to the widescreen feature of the re-release.
 * If Sonic delivers the final hit to the boss and hits twice instead (with the right timing), a glitch will happen which indicates that the boss needs to be hit another 255 times.
 * After defeating the boss, a glitch may happen involving that Sonic's movement is not locked from jumping into the bottomless pit; therefore losing a life.