This is a sub-page of Sonic Championship.
Death Egg II (Death Egg's Hanger Variant)#
Located right next to the final boss stage in the game's list of stage IDs, this appears to be a complete copy of said stage. The game seems to struggle with loading certain stage elements like the warning sign on the floor depending on the prior final boss stage's current state, which can either be in pre or post-cutscene mode. What makes this stage of particular interest is that it was likely intended to be playable in the game's Vs. Mode battles.
Supporting this idea is an unused title card referring to a "Death Egg II" stage. Should this stage be loaded into a Vs. battle, this graphic will appear before the fight begins. Additionally, as a result of how the stage music IDs are set as described above, this stage will actually play its intended theme when loaded. Aside from the above implication, these elements also correlate with evidence that an additional fight was planned in the arcade ladder that was scrapped.
Showcase Stage (NAMEENTRY)#
Labelled "NAMEENTRY" in the debug menu, this stage appears to consist only of a blue background and lacks a proper name or title card. Despite the label, the stage is not used for the name entry screen. It instead uses the ADV_MOVIE2 stage, which is also used for most other cutscenes in the game.
Aside from that, it appears to be an innocuous test/placeholder stage with little to remark on. Despite this, it does actually have elements unique to it such as its own distinct background colour which is a lighter blue than the game's typical default background, and pointers to load some 3D models, albeit ones that do not exist and simply appear blank. This could be a sign that it was intended to be a developed stage at some point, perhaps even the "Sunset Town" stage alluded to in the game's OST.
Mushroom Hill Variant#
A version of the Mushroom Hill stage with some differences. The background uses a texture for the sky instead of a solid colour like the used version. Said texture appears to be of the spores that the mushrooms around the arena release. This stage may be a leftover from an earlier version of the game, as some early screenshots depict the stage with a different background.
South Island Variant 1#
A version of the South Island stage with a few differences. The arena is noticeably smaller and more closed in than the used version. The bridge in the background is also missing.
South Island Variant 2#
Another version of the South Island stage. This one appears to be identical to the used version.
ADV_MOVIE2#
While not exactly unused, you can never play on this stage normally. As its name suggests, it’s responsible for cutscenes like the advertise screen and even the ranking mode screen.