Sonic the Hedgehog 2 · Sega Genesis · Build: Late May 1992 · Discovered: 2006 · drx / Hidden Palace
A very early build of Sonic 2, nicknamed after footage of it appeared on Nickelodeon’s game show Nick Arcade, offering a rare window into the game roughly six months before release.
This build, assembled around late May 1992, is one of the earliest surviving glimpses of Sonic the Hedgehog 2. It is riddled with leftovers from the first game — Sonic 1 level names, music, and object behaviour — and is deeply unfinished, with missing enemies, absent levels, and graphical glitches throughout. Its enduring fame comes from a playable, incomplete version of Hidden Palace Zone, a mythologised "lost level" that was cut from the final game and became the subject of years of fan speculation and hoaxes before this prototype proved it had genuinely existed. The ROM was dumped by the archivist known as drx and released publicly on 7 November 2006 as part of a landmark mass release of Sega prototypes, instantly reshaping how fans understood Sonic 2’s development.
For over a decade, Hidden Palace Zone was Sonic fandom’s great white whale — a level referenced in early magazine coverage and hinted at in the final game’s data, but never playable. It spawned elaborate fake screenshots and rumours about how to reach it. The Nick Arcade prototype settled the question definitively: Hidden Palace had been a real, partially built zone that Sega cut during development, not a myth.
The prototype’s 2006 release was part of a watershed moment for game preservation. The archivist drx, working with the Hidden Palace community, dumped dozens of prototypes at once, giving researchers unprecedented raw material. Sonic 2’s development could suddenly be studied build by build, and Hidden Palace was later reconstructed and even included, restored, in the 2013 mobile remaster — a cut level resurrected because fans never stopped believing it existed.