Knuckles in the Doomsday thanks to Debug
The Doomsday Zone is the final zone of Sonic & Knuckles and Sonic 3 & Knuckles. Under normal circumstances the zone is only playable by Sonic, but it is playable with Tails or Knuckles from the level select if Debug Mode is enabled. You must have all of the Chaos Emeralds to play the zone and can play as Hyper Sonic (Sonic 3 & Knuckles only) if you have all the Super Emeralds. The Death Egg has finally taken its final beating, and is destroyed for good. Now, as only Sonic and Robotnik remain, you must chase Robotnik in a race against time! Sonic must gather as many rings as possible to help last him through the fight. He must also keep dodging asteroids which slow him down if hit, and missiles which render him unable to move or grab Rings for a second. Although only a few hits are unlikely to jeopardise the player's chance of success, even a slight lack of concentration can cause Sonic to sustain many hits and push him dangerously far behind. Use A, B, or C buttons to push Sonic faster in any direction. Catch up to Robotnik as he flees in his missile ship!
The Doomsday in Sonic 3 & Knuckles.
There is a section of the first part of this level that has Sonic dodging missiles in a slalom sort of fashion, and Sonic must stay between pairs of missiles as they move up and down. Rings usually occur in groups of three or six, buying Sonic that many seconds if all are collected, although there are patches of eight or twelve at the top and the bottom of the level. It is still possible to earn an extra life by having 100 Rings, but it is very difficult to achieve this. 80 is a good amount to have in hand when confronting the missile ship.
The ship is strong enough that Super Sonic can't directly damage it. To defeat the ship you must make the homing missiles hit its "head" and avoid the ammunition it shoots. After you hit the head 8 times, the ship explodes and a giant robot similar to the Sonic 2 final boss in design with a jetpack emerges, carrying the Master Emerald. It releases bombs when you approach from above, and small spiny mines if you approach from below. You must race to get close to it and hit him 8 times to beat the level. This task must be done quickly, as Sonic generally loses rings a little bit faster than he can regain them.
This level marks the first time in a recurring succession of Sonic games that the final level uses a Super form setting in a race against time and depleting Rings, only accessible through obtaining all the Emeralds. A notable example of this is the 2006 game Sonic The Hedgehog, in which the final boss, Solaris, was fought between Sonic, Silver and Shadow, all in their Super Forms with 50 Rings to work with.
This game gives you 50 Rings at the beginning and transforms you instantly into Super Sonic or Hyper Sonic (the latter's case is if you have all of the Super Emeralds). Since Sonic is in Super (or Hyper) form, his rings are steadily depleted, and he must keep picking up Rings. As Sonic runs dangerously short of Rings, the music will accelerate in tempo, increasing tension in the player and urgency to keep collecting Rings. If Sonic's Rings are completely depleted, he loses his Super form, falls from space, and immediately dies.
What's interesting to note is that, within the Hidden Palace Zone (3 Zones previously), a mural in the
background during the battle between Sonic (or Tails) and Knuckles depicts this battle. This mural would make an appearance in the Archie continuity as Sonic and Knuckles are lead through the Hidden Palace Zone.
After Knuckles does this zone in debug mode, he is seen blue on the tornado and the original red one would be watching him at the end. He is also seen with two Master Emeralds, one in his hand and one on the back of the tornado.
Music
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