Egg Reverie Zone

The Egg Reverie Zone is the thirteenth and true final zone in Sonic Mania. It is only accessible to Sonic the Hedgehog, Miles "Tails" Prower, and Knuckles the Echidna upon collecting all seven of the Chaos Emeralds.

A void where time and space seemingly doesn't exist, the Egg Reverie Zone displays the final conflict between Dr. Eggman and the Hard-Boiled Heavies leader, the Heavy King, for possession of the Phantom Ruby, all the while the three heroes, in their respective super states, attempts to subdue the two and take the gemstone away from the power hungry monarchs.

Description
The Egg Reverie Zone is a barren wasteland where time and space ceases to exist. It is a purple-hued void, with rings floating around in an aimless pattern. A single platform exists within the zone, with several stage lights brightening up the platform.

Overview
After obtaining all seven Chaos Emeralds, Sonic the Hedgehog, Miles "Tails" Prower, or Knuckles the Echidna can transport to the Egg Reverie Zone after defeating Dr. Eggman in an octopus-like mecha using the power of the Phantom Ruby. Upon his defeat, the hero of the player's choice is taken to the Egg Reverie Zone, where Heavy King (in a super state-like appearance) would take the Phantom Ruby floating in front of the hero, shortly before Eggman in his Egg Reverie mecha arrives in an attempt to take the mysterious gemstone. Sonic, Tails, or Knuckles then transform into their super state and fight off both Heavy King and Eggman while dodging the vile duo's attacks.

Once Eggman and Heavy King are defeated, the Phantom Ruby creates a wormhole alongside Sonic, Tails, or Knuckles (each now in their normal appearance), thus, warping the heroes outside of the zone before the Titanic Monarch crumbles from the wormhole.

Boss
Being the true final boss of Sonic Mania, the Egg Reverie Zone casts not one, but two bosses to fight. Luckily, the player can utilize the hero of their choice with the seven Chaos Emeralds to become their respective super forms. The fight is tricky at first glance, but it can be a relatively easy finale for a seasoned player. Rings fly across aimlessly throughout the stage and can be used to refill the player's ring meter, which needs to be kept with at least one ring in order to keep their hero's super form: if the player choses not to collect rings, the fight will end, and the player will lose a life.

The player will begin facing the Heavy King; once the player hit the Heavy King or if enough time passes without the player making a move, it will switch to the Egg Reverie phase. Hitting one of the bosses will result in the other boss showing up, making the fight easier to manage.

The key to defeating the Heavy King is patience: Heavy King is surrounded by impenetrable space-time altering spheres that can make the player lose ten rings upon contact. The player can find an opening or wait until the Heavy King no longer has a shield to hit the boss. Hit Heavy King eight times and it will be destroyed.

As for the Egg Reverie, it is easier to hit than the Heavy King, but more difficult to avoid. The Egg Reverie's arms will swing and punch rapidly at the player. After being hit seven times by the player, the Egg Reverie will fly across stage, using the Phantom Ruby to blast a powerful beam towards the player. Hit Egg Reverie eight times and Eggman will be defeated.

Trivia

 * A "reverie" is the idea of a daydream or being lost in one's thoughts, which fits the description of the zone.