Unused Graphics

Beta Assets

Unused sprites for the title screen, using an early name of "Sonic the Hedgehog Discovery", most likely left over from the prototype shown to Sega.
Different background graphics for the title screen from the Sonic Discovery period of development, with a slightly more geometric island and a sky background that was later reused for the Pinball Bonus Stage in Encore Mode. Most interesting are the graphics of a Model 1 Genesis with a 32X and Model 1 Sega CD emitting a beam of light from the 32X's cartridge slot.

An early title screen shot featuring some of these background graphics, as well as the early Discovery logo, can be seen in a developer diary video published on the official Sonic social medias on July 19, 2018.

Ending graphics from early demos, which are still present in the final version files.

Act 3 Card

Sprites for an Act 3 are in the title card graphics. Although the boss arenas of Lava Reef Zone and Titanic Monarch are considered the "Act 3" of those respective zones, the title card still refers to them as "Act 2", rendering this graphic completely unused.

Old Pause Text

Early unfinished graphics of the English text, pause menu, and save select/2-player race are in Data\Sprites\UI\.

Piloting Sprites

Unused animations for Sonic and Tails looking up and looking straight ahead while piloting the Tornado, akin to Tails piloting the Tornado in Sonic 2. They both stay in their default animation cycle in the final game, akin to Sonic 3 & Knuckles.

Metal & Amy Signposts

All signposts but Sonic's are labeled with the respective character's initial in the sprite sheet. There are two placeholder copies of Sonic's signpost art seemingly labeled "M" and "A". These were originally intended to be signpost sprites for Metal Sonic and Amy, however they were scrapped and eventually replaced after being told by SEGA to replace them with Mighty and Ray for the Sonic Mania Plus DLC.

SPEED

Another unused text graphic. Sonic Chaos changed the standard time bonus from operating on certain time thresholds to being expressed as a 1 to 999 km/h speed bonus. Something similar might have been planned here.

Or it could have gone on the HUD and shown the player's speed. Y'know. Plausible.

Early	Final

Early	Final

Early graphics for the elemental shields and the insta-shield can be found in Sprites/Global/ShieldsOld.gif.

Early	Final

These early shield graphics are traced from the original Sonic 3 sprites, but with colors changed and more detail added. The final shield sprites were redrawn from the ground up and feature a lot of additional frames.

Early Fireball

This fireball from Hill Top Zone's boss in Sonic 2 was the original graphic for the burning logs in Green Hill Zone. The final game replaces this with a more detailed burning animation and a palette that matches the Flame Shield itself. It can be seen in Polygon's GHZ Act 2 gameplay.

Early Tails Intro

Both Sonic and Knuckles have special intros when entering Chemical Plant Zone, where a drop of purple water falls on their heads and they react to it (with Sonic's in particular being a callback to Sonic Spinball). This happens to Tails as well, however, he previously had no special animation in-game for it. From these sprites it's clear that he was always meant to have one, where he uses his tails to dry himself off.

A slightly different animation was eventually added to the game in the v1.04 update. The new spritesheet in 1.04 overwrites the unused one from earlier versions.

Blue Missile

An intact version of those blue missiles that the player has to launch at Heavy Gunner. It's obvious that both sprites are the same thing, but the intact sprite is supposed to be used until the player hits it, at which point it would use the busted sprite.

TV Monitor

An unused TV monitor with a background graphic and gradient (found in SPZ2/Objects2.gif) larger than the one seen in the Weather Mobile boss arena (found in SPZ2/WeatherMobile.gif). This is defined in the file SPZ2/GreenScreen.bin. Technically, these sprites are used, but by the also-unused GreenScreen object.

Big Squeeze Laser

The prongs of the Big Squeeze mini-boss are supposed to light up when it's charging - there are four frames of animation for it in the sprite sheet. Only the first frame is used in-game.

Wing Fortress Assets

The turrets from Wing Fortress Zone were set to reappear here. The tip is a separate sprite and would rotate to track the player in-game.

The last cut WFZ object is the infamous retracting platform.

Early BG

In the tileset for Flying Battery are some clouds that look much closer to their Sonic & Knuckles counterparts. This image has been reconstructed to show what they may have looked like in-game.

Jugglesaw

Graphics for an earlier version of Juggle Saw are in Sprites/PSZ1/Enemies-Old.gif in v1.03. The early design doesn't have googly eyes and its legs don't move, suggesting it originally stood in place.

Raised Blocks

While all of the alphabet blocks have raised animations ready, only A, O, and T are used.

Jars

Big jars of cyan, magenta, and yellow ink, larger than the ones that the Splats enemies spawn from. When Tails or Knuckles enters the jar, they'll be tinted cyan/magenta/yellow. Because of the way Sonic's palette is set up, he's unaffected by the ink jars.

The graphic is supposed to combine with the jars something like this. The actual blending in-game looks better, obviously.

A high-speed ink wiper. These would presumably clean the ink off, but it doesn't seem to do anything as-is.

ON / OFF lights for both printers. The brighter lights are for the Mk II printer.

Chain Plat

An Act 1 version of the swinging platforms seen in Act 2.

Graphics for the wood chippers and wall shuriken shooters from Act 2 are also present within Act 1's assets.

Masks

Comedy and tragedy mask constellations meant to be seen in the skies of Act 1.

Spinning Sign

The spinning signposts seen throughout the Sonic CD version of Stardust Speedway make no appearance here. There's a signpost object in edit mode, but it uses old graphics from the Sonic CD remaster and it isn't attached to anything.

Hotaru

A whole lot of frames for the annoying Hotaru badniks go unused, as they only ever point their bottoms directly downwards. These correspond to the original version of this enemy in Sonic CD's Stardust Speedway, which can be placed in debug mode and behaves accordingly. However, like the signpost, it still uses the old graphics from Sonic CD instead of this updated set.

Early Hooks

Early hook graphics are left in the HCZ/Objects.gif file. The early graphics have the useful hook in the foreground and the useless hook darkened in the background, while the final version changes this so they're both in the foreground but the useful hook is flipped, fatter, and green.

Pinata

It seems that the first design for the piñatas was of a Ball Hog, which looks similar to a design seen in early footage of Sonic 1. A more traditional star-shaped design is used in-game.

Tilesets

The tileset used in the Mirage Saloon inter-stage cutscene for Sonic and Tails in the Switch version of Sonic Mania is an early version of the one used in the rest of the Zone. These include some major differences such as wooden quarter ramps and a barrel in place of decoration tiles, but also minor changes like the palette of the background having a darker darkest shade of blue and slightly different decorations.

Booster

A horizontal version of the booster objects that propel the player into those ball launcher things. Unused in Sonic 2, and also unused here.

Embers

A separate foreground layer of embers, meant to fall in Lava Reef Zone. Could have given the Zone a hotter, more volcanic feeling.

Conveyor

Spiked platforms on conveyor belts, seen in Act 2 of the original Lava Reef but not in Sonic Mania. It was seemingly intended to be used; corrupted remnants of the platform conveyor can still be found in the low layer in Act 2.

Chain Link

This giant chain link is in Heavy Rider's sprite sheet. As the Little Planet is in the background of the stage, and the following Zone is Metallic Madness, perhaps this was part of a cut exit sequence for Sonic and Tails based on the animated intro to Sonic CD? It can even be found in a BG layer, which lines up perfectly with Little Planet's location.

Editor Icons

Two icons for a stage editor can be found in LRZ2/Objects.gif. The "CVYR" graphic shows up in edit mode, but for some reason the white text isn't displayed, so it's just a black circle. The "DROP" graphic doesn't appear at all.

Animated Cylynder

A spinning version of the cylinders in Metallic Madness, labeled as "Barrel" in MMZ/Platform.bin. Probably for the best that the devs didn't bring back Carnival Night Zone's most infamous aspect.

Tiles

A big chunk of tiles in the Egg Reverie tileset go unused, suggesting that the original plans for the zone might have been quite different. For instance, these support structures that hold up the platforms in the boss area are too far below the camera for the player to see.

There are even quarter-pipes, both normal and crystallized. Note that the normal versions of the slopes and quarter-pipes are actually just palette swaps of tiles seen in Titanic Monarch Zone.

Leftover sprites were found in the game's sprite folder, showing sprites for Scrap Brain Zone. These sprites are leftovers from Sonic 1 on iOS and Android, as the layout of the sheet is identical. It's worth noting Metallic Madness Act 1's boss is a rematch against Sonic 1's final boss, so this sheet may have been used as a reference. Working animation files for the Bomb, Ball Hog, Caterkiller, Conveyor Wheel, Eletric Orb, Flamethrower, Junction Wheel, Orbinaut, and trapdoor objects are also all present and pull sprites from this sheet.

These sprites were removed in a subsequent update.

Unaltered sprites of the remade Hidden Palace Zone from the mobile remake of Sonic 2. These may or may not have been a simple leftover; although a Hidden Palace Zone was planned to be included in Mania, it would've been an original take and not this Hidden Palace Zone. Of all of these assets, only the Jellygnite Badnik was updated, as it appears in Hydrocity Zone. Animation files for the Batbot, Jellygnite, Redz, and Segways also exist in the folder. These all exist in the HPZ folder, separate from that of the Sonic 3 Hidden Palace, which is in the LRZ3 folder.

Emerald & Super Emerald

Included in the Blue Sphere bonus stage files are sprites of the Chaos Emeralds and Super Emeralds redone for Mania with two extra frames and a different color palette. According to the sprite sheet, these emerald sprites were polished up versions of the unused classic sprites. This could've meant the Blue Spheres Minigame was meant to be reused as the Special Stage format, rather than the new Special Stage format we see in the final game. If you use an editor to place them into a stage, they function like red spheres by taking you back to the last checkpoint.

Classic Sprites

The original Blue Sphere sprites used in Sonic 3 & Knuckles are present in Objects-Classic.gif. As with other Classic object sprites, these were originally made for the Retro Engine remasters - in this case, the prior proof-of-concept remaster of Sonic 3 which would eventually be completed for Sonic Origins.

Escape Message

A somewhat ominous message. As revealed by Christian Whitehead, the Special Stages were supposed to end with the UFO getting angry and chasing the player down, which would presumably display this message.

Early UI

Graphics with buttons and screens, suggesting an interface resembling the Sega CD's actual UI (specifically the US Sega CD 1 one). The final game uses a more generic interface.

Screen Modes

Graphics for stretched 3 player screen modes, and a blank 4 player screen mode are present in the game's files. These are not able to be selected, and do not appear in the decompilation here. The blank 4 player mode graphics may have been a base for other screen mode graphics.

Test Objects

Various leftover sprites from the mobile ports of Sonic 1, 2, and the failed mobile Sonic 3 pitch located in Blueprints of the game's sprites folder. The sprite sheet is based on the objects sheet for the unused Egg Gauntlet Zone boss rush level. Additionally, there is also a scaled-up springboard sprite added, possibly as a test for Studiopolis' clapperboard object.

Straight from The Taxman's keyboard-mouth:

The Blueprints thing isn't special at all really. "Blueprint Zone" was something that existed very early on while I was developing RSDKv5. We just ported a bunch of stuff from the remasters to test the tools out, and simply forgot to delete the sprite sheet when it wasn't needed anymore.

As of v1.03.0831, the folder and image file no longer exist in the data.