Wing Fortress Zone

Wing Fortress Zone is the tenth Zone in Sonic the Hedgehog 2. Unlike the early Zone of the game, Wing Fortress consists of only a single Act, with a boss fight at the end.

Description
After his defeat in Metropolis Zone, the evil Dr. Robotnik flees to the skies in his secret stronghold, which is a flying battleship. Sonic and Tails pursue in the Tornado, chasing the mad scientist through the skies and catching up with the Wing Fortress. However, just as our heroes are getting close, Eggman opens fire with a laser barrage, blasting Sonic's biplane out of the air. Whoever the player is controlling (Sonic or Tails) will make a leap from the little plane's wings onto the rear gantries of Robotnik's aerial stronghold. The player will have to explore Wing Fortress alone, even if playing with Sonic and Tails.

The beige aircraft contains all too many opportunities for Sonic to fall to his death, be it swinging hand-over-hand on the bars right next to the flaming booster engines, or jumping along retractable platforms set in the side of the ship, or being thrown over wide, open spaces by the launcher chairs which lie amidst the steel rigging. Vertical propeller blades are also on hand to chop the player up into pieces when they run into them.

Boss
In this Zone's boss fight, Dr. Robotnik eschews his usual Egg Mobile and attacks with the level itself. After breaking into the interior of the airship, Sonic finds himself trapped by a pair of forcefields, while Robotnik deploys cruelly spiked platforms and a laser beam to cut the hedgehog down. This is quite a difficult one, the trick is to jump atop the floating platforms when the laser opens its shield casing, and wallop it before it fires. After enough hits, the machine overloads, blowing up the forcefields and sending Robotnik running.

After defeating the boss, Sonic chases Robotnik onto an exterior gantry as the scientist makes his escape aboard a docked one-man spaceship. This marks the timely reappearance of Tails in a (now rocket-powered) Tornado. Once again pursuing through the skies, Sonic leaps onto Eggman's spacecraft as Wing Fortress Zone falls from the sky, hitching a lift to the final stronghold.

Trivia

 * One of the more difficult portions of this level, the handrail section close to the beginning, can in fact be bypassed entirely, which is a great help both to Sonic's life count and to the player's time if they're an aspiring speed-runner. After the player destroys the very first Clucker chicken Badnik, balance on the extreme right of its emplacement, the player can jump up to a platform containing a Shield TV. From here, jump straight up, and an overhead propeller sweeps the player further upwards to the higher level, thereby avoiding one of Wing Fortress Zone's more annoying segments. The area where this shortcut is found is actually seen in the Sky Chase Zone as the Wing Fortress comes into view. Be sure to venture left rather than right after doing this, otherwise you will come to the section just skipped!
 * Dr. Robotnik's Japanese name is written on the Zone, despite being called "Robotnik" elsewhere at the time.
 * Note also in the picture to the right the early symbol of the Eggman Empire. Instead of a cartoony depiction of his face, the mad scientist instead used a stylized "EG" on the bulkheads of Wing Fortress.
 * This zone is an inspiration to Sky Fortress Zone Act 2 and 3 from Sonic the Hedgehog 4: Episode II.
 * Strangely, the two parts of the Wing Fortress Zone are not properly connected, not even through frame.