S2B/Sonic 2 Beta Zones/Hidden Palace Zone (Final)

The unfinished Hidden Palace Zone can be accessed in the final version of Sonic 2, using any of the following methods:

• Game Genie: ACLA-ATD4
• Action Replay: FFFE1 00008
• Game Shark: 160FFE10 0800 (Sonic Jam)
• Savestate Editing: Open a debug-enabled EHZ act 1 savestate, change 12280 offset 8 to 08.
• Savestate: Download

Tom41 was the one who discovered how to access it by hex editing. The zone itself is there but the graphics for it have been taken out.

[...] and you won't see a HPZ bridge or 'master emerald' in S2 Final. The blocks are there, but the graphics have been overwritten with glitchy data from OOZ - making them look nothing like bridges/emeralds/crystals etc.

Tom41, ROM Hacker @ Area 51 Ikonboard (defunct)

Different from our prototype? Nope

This Hidden Palace is exactly the same as the prototype one sans auto-spins.

Because what remained of HIDDEN PALACE in Sonic 2 End it indicates that the Level was not altered among our Beta and the Final, The only thing that it was added among it beta and the final was the Auto Spin in the Tubes [...]

Esrael, ROM Hacker @ Area 51 Ikonboard (defunct)

Boss data found? Nope

Some believed there was a boss in HPZ, because of the fact that the screen "locks" at certain position near the end. However, this does not mean there was ever a boss.

All levels lock at the end when the X limit to the right has been reached. The end sign panel, the egg container, and the boss objects do not control that.

Luigi Link @ Area 51 Ikonboard defunct)

Hidden Palace here I come!	Sonic curling up when going down the tube. Does this mean Hidden Palace was worked on between beta and final? Nope, unfortunatly autospin is just engine work, rather than HPZ work.
The rings inside the tube are still here.	Unlike in the prototype HPZ, this Tails 1-up monitor does not give Sonic an extra life.
The glowing orbs appearing as scrambled blocks of pixels.	The famous glowing bridge.
You can get through the zone by placing and destroying the egg prison object.

Note that it plays music #10, instead of Mystic Cave 2P in the prototype. Which music was really intended for Hidden Palace? It's something that is open to speculation.