- This page deals with the Hidden Palace Zone of Sonic 3 & Knuckles. For details on the unfinished level from the prototype version of Sonic the Hedgehog 2 (16-bit), please see Sonic 2 Beta.
Hidden Palace Zone in Sonic & Knuckles is a transitional level between Lava Reef Zone and Sky Sanctuary Zone. It consists of a single act, and is the shortest level in the game. It is also the only level in any of the Mega Drive-era Sonic the Hedgehog games that is devoted to plot progression. The stage first appeared in the Sonic 2 Beta.
In Sonic's storyline (which can also be played as Tails if Sonic 3 is locked on to Sonic & Knuckles), Sonic arrives in the Hidden Palace from the Lava Reef Zone. He encounters Knuckles the Echidna, who still believed Eggman's claims that Sonic is evil, and there is a boss battle in which the two fight each other. (The room of the boss battle is particularly notable for the prophetic mural in the background, presumably created by the defunct Echidna society, which foreshadows the final battle between Doctor Eggman and Super Sonic in the Doomsday Zone.) After Sonic wins, a cutscene is shown in which Eggman steals the Master Emerald from the Emerald shrine, thus revealing his true intentions to Knuckles, who tries to stop him only to be electrocuted. When Knuckles recovers, he leads Sonic to a teleporter which transports them both to the Sky Sanctuary Zone.
In Knuckles' storyline, the level is even shorter. It contains no enemies or obstacles, and no other objects besides the teleport to Sky Sanctuary, which is Knuckles' final zone in the game.
The Hidden Palace Zone also appears throughout the second half of Sonic 3 & Knuckles (after the beginning of the Mushroom Hill Zone), when the player collects one of the Super Emeralds. After entering the first special stage after completing the Launch Base Zone, a cutscene is shown in which any collected Chaos Emeralds are transported to the Hidden Palace Zone's Emerald shrine, although they are depowered and grey. Jumping on a greyed-out Emerald will transport the player to that Emerald's special stage, the completion of which will grant the player a Super Emerald and turn the greyed-out Emerald into its original bright colour.
- In Sonic 3 & Knuckles Hidden Palace is coded under Lava Reef 4 on the level select screen (Lava Reef 3 is the boss fight of Lava Reef 2.)
|Emerald/Ring||Chaos Control | Chaos Emeralds | Master Emerald | Rings | Minor power objects | Special Stage | Star Posts | Super transformation|
|Locations||Earth | Mobius | Little Planet | Angel Island (Hidden Palace) | South Island | Mystic Ruins | Central City | Station Square | Space Colony ARK | Tiny Chao Garden | Knothole | Mobotropolis | Shanazar | The Void | Westside Island | Nameless Zone|
|Vehicles||The Tornado | Egg Carrier | Dr. Eggman's vehicles|
|Other||Aliens | Eggman's robots (Badniks) (E-Series) | Mobians (Echidnas) | Eggman Empire | Roboticizer (Roboticization) | Sonic Team | Voice Actors|
|Spin offs||Manga | AoStH (episodes) (Blast) | Sonic the Comic | SatAM (episodes) | Archie (Knuckles) | Movie | Underground (episodes) | Sonic X (episodes) (comic) (card game) | List of printed media|