Electric Egg Zone

Electric Egg Zone is the sixth level of Sonic Chaos for the Sega Game Gear / Sega Master System, coming after Aqua Planet Zone. In keeping with the other stages of this game, Electric Egg consists of two standard Acts followed by a shorter, third Act which contains the boss. Geographically, this Zone is located on South Island (as is the rest of Sonic Chaos).

Electric Egg is a sprawling techno-fortress, and the Doctor's final base in the game. Automatic laser cannons, bottomless pits, and spikes aplenty await Sonic and Tails as they close in on Eggman himself. The zone is criss-crossed by a network of winding vacuum tubes, reminiscant of Scrambled Egg Zone from the previous Master System adventure, Sonic the Hedgehog 2 (8-bit).

Boss
Throughout Sonic Chaos, and in a marked change of his tactics from other early games, our old friend Doctor Robotnik apparently thought himself too important to face Sonic or Tails personally, instead deploying larger, tougher, nastier badniks as boss robots. However, now the Mobians have infiltrated his final stronghold, the fat man has nowhere to hide, and finally hauls his obese bulk into battle.

The first part of the boss is the 'Egg Turkey', a kind of scaled-down AT-AT Walker which fires bouncing bolts of energy. These are actually quite difficult to dodge, as they persist for a considerable while, ricocheting all over the screen. Robotnik's mecha can take 16 hits before it explodes...

...but then the mad scientist disengages his Egg-O-Matic and makes a last-ditch effort to ram Sonic to death. The last time he tried that tactic, it didn't work so well; this time, the Doctor's pod is larger, meaner, and a lot faster. However, if you can smack him on the head one more time, Robotnik is defeated.

Sonic proceeds to chase the escaping (and surprisingly nimble) human across Electric Egg's metal plates. If you've not collected the five available Chaos Emeralds from the game's Special Stages, Sonic trips over and falls on his face rather embarrasingly, allowing Robotnik to get away. If you have been collecting the gems, the Doctor still escapes aboard a floating platform, but he drops the sixth, red Emerald while doing so. Presumably, reuniting this Emerald with its counterparts stops South Island from sinking into the sea. Hooray for Good Ending!