The Hidden Palace Zone boss is an optional boss in the 2013 mobile re-release of Sonic the Hedgehog 2, replacing Drill Eggman II should the player branch into Hidden Palace Zone rather than finish Mystic Cave Zone Act 2. The player has to hit the Egg Mobile eight times to defeat Dr. Eggman.
Dr. Eggman flies in front of a giant archaic organ. He will hover just out of normal jump height. The massive trombone on his Egg Mobile will activate every few seconds. He begins with four descending notes, causing four hazardous spiked balls to fall from the ceiling and land in the water below the arena. The water will then rise over the platform, taking the floating balls with them for a second or two. After being lowered to the original water level, the balls will detonate and emit a vertical splash that must be avoided. After a few more seconds, a long and loud bellow will emit from Eggman's trombone, causing the screen to shake until one larger spike ball descends. This variant homes on the player's character until it also explodes, thrusting a large jet stream into the air. After this, Dr. Eggman will encore indefinitely.
Per usual, eight hits will mute the machine. During the first phase of attack, the player can take advantage of the buoyancy of the water to reach the Egg Mobile, although the small flames at the bottom of the Egg Mobile will damage the player, unlike other bosses from this game. The main method of attack comes in the second phase, where the player can lure the Egg Mobile above the large homing bomb as it erupts. If hit, the Egg Mobile will drop to the ground briefly, giving the player enough time to land multiple hits before Eggman returns to the air and repeats the process. Super Sonic and Tails can reach the boss easily, negating the need for waiting.
- This boss is referred to as Brass Eggman by fans, in reference to the bosses naming scheme in-game.
- This appears to be an entirely new boss design by Christian Whitehead, as no concepts for a boss machine were finalized or even intended for Hidden Palace Zone.
- A similar pipe organ appeared in "Sonic's Song" from Adventure of Sonic the Hedgehog, where in two scenes, Robotnik was trying to come up with a song once he gets rid of everyone else's music (including the titular Sonic's Song). It might have been coincidental that a pipe organ was used as a centerpiece for the Boss Fight in the 2013 re-release of Sonic 2 even though Grounder has a Green variation sprite (as a reference to AOSTH) Debug Mode.
- The musical construct in the background appears to be based on the famous organ of Alexandra Palace.
- There is a glitch with inflicting the final hit while the Egg Mobile shakes just after being paralyzed, causing the damage counter to roll over and become indestructible much like the Final Zone from the original Sonic the Hedgehog game.
- This is the only boss in the 2013 re-release of Sonic the Hedgehog 2 not to be battled in Boss Attack Zone.
- ↑ While a boss name has not yet been used by Sega itself, the Sonic Retro community coined the term "Brass Eggman" with a nod of approval.
- ↑ Craig Stitt, the original designer of the deleted Hidden Palace Zone from Sonic the Hedgehog 2, stated that many (if not all) of the enemies are different, but enemy appearance and behavior were possibly not finalized. To his recollection, he can conclusively confirm that the addition of the boss and organ are new assets and not part of the planned zone. http://forums.sonicretro.org/index.php?showtopic=32947&st=45