Sonic 3 Unlocked (SHC 2026 Demo)

By Liliam (they/them)
 

Sonic 3 Unlocked is an extensive modification of Sonic 3 that brings concepts from modern day "classic" Sonic titles back into the Mega Drive original. Joining Sonic, Tails and Knuckles are newcomers Amy Rose, Mighty the Armadillo and Ray the Flying Squirrel, complete with their movesets from Sonic Origins and Sonic Mania.

Encore Mode from Sonic Mania Plus also makes a return, allowing you to play a remixed version of the game as any combination of technicolor mice. Press the A button to change which character you're controlling.

Many, many bugs in the original game have been fixed, and several quality-of-life changes have been made, both to the presentation and to various gameplay elements, with the goal of producing the defintive version of Sonic 3 this side of the console generation canyon.

Changes include:

  • Cutscene skips: Most cutscenes in the game can now be skipped. Whenever the HUD is hidden from view, simply press Start followed by the A button to skip ahead. Score countdowns can also be skipped with a press of the Start button.
  • Let's keep not wasting time: Every pushable object now moves a lot faster. Various sequences have been slightly sped up, such as the Sandopolis 1 boss. You can jump out of objects you previously couldn't, such as the rappel wires in Sandopolis and the 3-2-1 countdowns in Death Egg.
  • Game overs are scary again: Using a continue will now send you back to the start of act 1, as if you had reset the game and reloaded your save file. Accordingly, continues are no longer awarded in saved games; you have an infinite number of them. Getting a time over will now always send you back to the beginning of the current act with a zeroed-out timer.
  • Tails assist: Double jump moves are blocked if you hold the Up button and no other directions. This is to facilitate being picked up by Tails, whose flight can now be controlled by player 1 even when Tails is the support character.
  • No Knuckles, Stop Turning Super: The A button now functions as a dedicated super transformation button. This means you can keep using double jump abilities without having to activate your Super form if you don't want to.
  • Master of unlocking: A hidden ability is available for each character and can be unlocked by clearing 1 Player mode as said character. Hidden abilities may also be unlocked in bulk for each character that is retained through the end of Encore Mode.

Known issues:

  • Tails and Amy have a shorter roll height than the other characters, which causes them to trip on level geometry more often, especially at high speeds. I'm not sure what a fix for this looks like at the moment.
  • Knuckles' climb gets immediately canceled when he touches a solid object. This was introduced to fix occasional collision issues, but is too big of a change and will be replaced with a different fix in later versions.

Things that are missing from this demo:

  • Alternate level palettes for Encore Mode are not available yet. I just couldn't get them done in time.
  • Encore Mode still uses the original Special Stage layouts from Sonic 3. There will be original layouts in the final version.
  • I plan on rebalancing monitors in Encore Mode to make the new items more easily obtainable. I also plan on moving all the Special Stage rings around.
  • 'Museum' on the title screen is something that I hope you'll appreciate once it's ready. Please look forward to it.
  • Even more things are planned for the future???

Big thanks to all the people who helped me get here, especially those of us whose rights are being challenged right now.

Art is resistance. Keep creating.

Credits

Amy and Mighty/Ray's sprites are taken from Sonic Origins Plus and Sonic Mania Plus respectively, color-reduced to fit the Mega Drive palette by me. Some of the poses for these characters, as well as most other original graphics in the game are made by me, even where equivalents exist in those games, such as the extra Super Sonic poses and the extra ring frames.

The exceptions are listed in the in-game Credits option accessible from the title screen: the large ending sprites for Mighty and Ray were made by Delta Conduit, and Amy's 1-up icon and end sign/bonus plate were made by E-122 Psi, though not specifically for this project.

Several additional graphics are also sourced from official Sonic games, such as the background of the Encore mode bonus stage, or the shattered Super Emerald sprites in Hidden Palace Zone.

Some music tracks have also been imported from official Sonic games, including tracks from the November 3rd, 1993 prototype of Sonic 3. This was facilitated by the reverse engineering work on the SMPS format by Natsumi, Clownacy, and several others. Sonic 3 Unlocked uses Flamedriver, a bugfixed version of the Sonic 3 sound driver by flamewing. A full list of credits for code reuse is available through the in-game Credits option, under the 'disassembly contributors' section. Special thanks to hiddenpalace.org for obtaining and dumping the prototype build of Sonic 3 from which most of the extra music tracks were sourced.

Sonic Mania Plus code was decompiled and reverse engineered in order to provide accurate implementations of Sonic's drop dash and Ray's air glide abilities. The drop dash was decompiled and converted to Mega Drive assembly code by MainMemory, while the air glide was decompiled by Rubberduckycooly and converted to Mega Drive assembly code by me.

Any other gameplay features were eyeballed and did not reference any code from Sonic Mania, Sonic Origins or other titles. However, Sonic 3 Unlocked is very obviously inspired by those games, as well as by fan projects Sonic 3 Complete and Sonic 3: Angel Island Revisited. To all the designers, artists and developers behind these works: thank you!

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Download

File Type: rom/mega-drive

File Size: 4 MB

Tristan2 @ 2026-10-22 17:40:50

ENCORE MODE WAS REALLY OUT!!!

Mildanner @ 2026-10-22 19:45:26

Best ROM hack ever, I saw this on github