Barrier Eggman

Barrier Eggman (バリアエッグマン) is the eighth boss in Sonic the Hedgehog 2, that the player has to encounter at the end of Wing Fortress Zone. Barrier Eggman also appears as mid-boss at Flying Battery Zone Act 2 in Sonic & Knuckles, where the player is unable to destroy it.

In both games, the fight involves the player trapped in a small room behind an impenetrable force-field-like barrier. Within the room is a moving laser that is operated by Dr. Robotnik from a control panel just on the other side of the barrier. Once the boss is defeated, the barrier fails, allowing the player to proceed, and Robotnik escapes.

Sonic the Hedgehog 2
The player encounters Barrier Eggman at the end of Wing Fortress Zone in Sonic the Hedgehog 2. It is located at the cabin room of the air fortress and where Robotnik also is seem to be piloting it before the boss. After the Star Post, the player has to blow small mine on the roof to enter the cabin room. After taking small amount of rings, the player finds himself being trapped between activated laser walls, while Robotnik himself is laughing on the right side of the room.

Small hatch on the ceiling opens and small spinning platforms with spikes below them will arrive to float around the trapped room. Moving cannon also appears to the ceiling of the cabin room, that eventually stops to load it's laser wave. It will then shoot the laser wave to the floor and starts again moving at the ceiling at the same time. After five seconds, It will stop shooting, shuts it's laser cannon and repeats it's pattern over again.

The only way to get out of this trapped room is to destroy the laser cannon. This is possible, when it stops and starts loading the laser cannon to it's full power. The player has to use spinning platforms to reach the cannon, but the player has to watch out to not touch spiky-parts of platforms, which can hurt the player. The player also has watch out to not get hurt the laser blast, that the cannon will shoot after loading it enough. It is able to see by it's flashing speed, that it has during it's loading.

By doing traditional eight hits to the cannon will end the battle, but also spinning platforms and the trap room itself got damaged as well. Robotnik doesn't wait to see results, as he is seen escaping to his space shuttle to travel to his space station Death Egg. After the player is free from the trap room, Sonic arrives too late to the launch pad to stop doctor, who has launched his space shuttle off. After this, Tails arrives with Tornado, that has rocket add-on set below the biplane. After the sky chase, Sonic snatches grip on the ship and keeps hanging on until the space shuttle is docking to the space station. The player will then progresses to last zone in the game.

Sonic & Knuckles
Barrier Eggman later returns in Sonic & Knuckles as sub-boss, that the player encounters at the end of Flying Battery Zone Act 2. The player will get trapped to the room on the exit hall. Robotnik is now also seen controlling the moving laser cannon at the ceiling himself this time. When the player has Knuckles, Egg Robo normally is seen controlling it.

In this version, there are no more spiked platforms (meaning that the player cannot attack the laser eye directly). Instead, the room becomes smaller every time that the laser is fired. To survive this event, the player only needs to avoid the laser fire for a certain number of times. Though the player must avoid the laser to win the fight, it is possible to hit the laser cannon's eye, but it doesn't do anything.

Eventually, so much of the room is damaged that the barrier falls on its own and Robotnik on panic, escapes to the outside of the air fortress. After that, the player will follow Robotnik to the outside and has to pass through the last platforming section of the zone, where long platform will raise up while the player has to keep running the route or he/she will eventually get crushed between the long platform and ceiling. After this, the player will be able to ride up with the long platform for the moment, when the zone's boss Hang Mobile arrives.

Sonic the Comic
The Sonic the Hedgehog 2 version of Barrier Eggman was featured in Sonic the Comic #6, "Attack on the Death Egg", in which Sonic returns to the Wing Fortress some time after the events of Sonic the Hedgehog 2 to find that the defenses have been left running on automatic. Having defeated the system before, he easily does so again by leaping onto a spiked platform and then hitting the laser cannon with a Spin Attack.

Trivia

 * In Sonic The Hedgehog 2, if Sonic jumps to the pilot seat after beating Barrier Eggman, there is an Extra Life.