Retrun-Sonic
Packer/unpacker for RSDK based games (like the Sonic CD remake)

Programmed by nextvolume

This a packer and unpacker for RSDK (Retro-Engine SDK) based games, and it works with the datafile formats of Retro-Sonic (SAGE 2007 demo), Sonic Nexus (SAGE 2008 demo), SEGA's 2011 Sonic CD remake,SEGA's 2013 Sonic 1 remake (also known as Sonic the Hedgehog 2.0) and SEGA's 2017 Sonic Mania.
It also works with the Sonic 2 remake, but not many filenames are known, thus most will be dumped as X.bin (where X is a number).

Complete filename mapping for Sonic 2 is going to come in a newer release.

Sonic Mania and Sonic 1, internally they are handled as almost the same, it is the magic string in the datafile header and the encryption what differs.
But for Sonic Mania you need the correct filename to decrypt the file due to the way the encryption works.
A list can be found here (thanks to the rsdkv5_extract authors, which is another packer/unpacker with no relationship to this).
Use it with the -L option

Meanwhile, enjoy Egg Gauntlet, the zone officially scrapped from the remake, thanks to my guide
It's still in the game, by the way, because such is the SEGA Way(TM)

The Retro-Engine SDK was programmed by The Taxman, whose real name is Christian Whitehead, formerly a member of the Sonic hacking community.
Is there are a Sonic hacking guide for Sonic CD 2011 yet? No, not yet. But you can play with all the data now, so happy hacking!
Many thanks go to Xeeynamo, who helped me to figure out the encryption used by the Sonic CD remake.
Also, many thanks go to ValleyBell, who helped me to figure out the encryption used by the Sonic 1 remake.
Just like the Sonic CD remake, there isn't a Sonic hacking guide for Sonic 1 (Sonic the Hedgehog 2.0) yet!

You may also want to check out TaxEd, a level editor for RSDK based games.

Downloads
The latest version is 1.51.

Retrun-Sonic 1.5, Windows x86 32-bit binary and source code included (+precompiled mhash library for MinGW32) (August 31th, 2017)
Retrun-Sonic 1.5, Windows x86 32-bit binary and source code included (+precompiled mhash library for MinGW32) (August 31th, 2017)
Retrun-Sonic 1.4a, Windows x86 32-bit binary and source code included (+precompiled mhash library for MinGW32) (May 27th, 2013)
Retrun-Sonic 1.3, Windows x86 32-bit binary and source code included (+precompiled mhash library for MinGW32) (May 23rd, 2013)
Retrun-Sonic 1.2, Windows x86 32-bit binary and source code included (+precompiled mhash library for MinGW32) (May 22nd, 2013)
Retrun-Sonic 1.1, Windows x86 32-bit binary and source code included (May 18th, 2013)
Retrun-Sonic 1.0, Windows x86 32-bit binary and source code included (March 24th, 2012)

If you run something else than Windows, simply recompile. The program works on both little and big endian machines.

For the sake of research and openness I make all my hacking resources freely available and open source.
It wouldn't be much to expect, you know, if you did that in turn. Too often hacking has been ruined by selfish and overzealous individuals.
Hacking is kind of like science, made up of cold, hard facts. Remember that scientists not releasing their research publicly are not taken seriously.
You shouldn't want to end up looking like our friend Scratch depicted above.

If you want to get in touch with me, it's easy. My email is tails92@gmail.com
My MSN contact is also tails92@gmail.com

You might also be interested in my Sonic Nexus Curiosities page.
Mostly about Sonic Nexus, but also about the other RSDK based games.
Interesting read if you're interested about the Retro-Engine.
Old information about the Sonic 1 remake, but interesting nonetheless.
TaxEd - Level editor for Retro-Sonic based games

Last Updated: September 1st, 2017
Back to Unhaut