Retro Engine and Sonic Mania


Retro Engine is a game engine developed by Christian Whitehead. Five different iterations of RSDK (Retro Development Kit) exists:

Links and downloads

GitHub repo RSDK Animation Editor Data.rsdk unpacker

Data archive (data.rsdk)

Data.rsdk for RSDKv3 and RSDKv4 are way different.
RSDKv3 uses an encrypted virtual file system that recalls a zip archive with the name in clear. This is the first public released RSDK unpacker and the encryption/decryption has been cracked by me.
RSDKv4 hashes the file names in MD5 and a list of files is required to re-build the original data folder.
Both of my researches contribuited for the developent of Retrun-Sonic

Animation system (*.anm files)

Despite the appearance of the format and its purpose, multiple versions of it exists. I cracked the formats used by RSDKv3, RSDKv4 and RSDKv5.

Stages system

During 2012 I worked on a level viewer of Sonic CD that has never been released to public. I will insert more info here in the future.

Scripting system

During 2012 I worked on a script disassembler of RSDKv3 that has never been published until the beginning of 2018. The reason is that it is not complete and it is quite buggy. One day I will complete it. Maybe. The real reason is that there is no much interest from the community to decrypt it. Another reason is that the scripting format is very different from the other RSDK versions and covering only a single game it is not worth that much. Still I am curious on how some AI or script works, so maybe I will look into in the future.
Source code


Few days after the Steam release of Sonic the Hedgehog CD, I released a short video showing a proof-of-concept mod with Metal Sonic as playable character. The mode featured a private animation editor (later re-used for RSDK Animation Editor) and was never released to the public.

With the re-release of Sonic the Hedgehog 1 on Android, I was able to crack and unpack the new Data.rsdk format in a short time, extract the animation file from Knuckles and import it into Sonic the Hedgehog CD as a proof that the RSDKv3 and RSDKv4 animation data were interchangeable.

Many years later, with the release of Sonic Mania, various modding communities born. Reddit has one community about Sonic Mania modding.

Sonic Mania

On 12 Apr 2018, at 09:23:37 the unfinished 1.04 version of Sonic Mania (european version) was uploaded on Playstation's servers by a "mistake".

Using a PSN crawler, I was able to catch the 1.04 update and store it. It never happened that Sony removed game updates from the store, so the link should never die. I downloaded the update file anyway.

In order to download and install it on your Playstation 4, you need to install Charles Proxy, using it as a proxy and overriding the 1.03 update with 1.04.

1.03 version that needs to be remotely mapped:

1.04 version:

The most handy way to do that is to go on your PS4 connection settings, set the proxy using the local IP of your PC (look for ipconfig), start to download Sonic Mania from PSN / Library, catch the ppkgo update and replace it with the new one. The following screenshots will help you if you are new on this kind of stuff.

tutorial 1

tutorial 2

tutorial 3