I'm pretty sure there was a topic about this earlier this year but essentially it comes down to this:
The whole "releasing the RSDK" idea was due to the original planned feature of having a "custom levels" option for the Retro-Sonic fan game. Back then, the game's editor was quite primitive. You could only make new levels for the existing game.
By the time I was working on Nexus and XG, the RSDK/Retro Engine had progressed to the point where it was no longer Sonic specific, and by the time I was working on Sonic CD, it had progressed to the point where it was a full on game development environment for my professional work.
In all honesty, most people that want to use the RSDK and engine are looking for a "Sonic Worlds" type of base to make their fan games. But the recent iterations were never made with the intention of it being a 'drag and drop' tool for beginners / non-programmers (I guess the difficulty would be somewhat on par with something like Unity or UDK). And while I own the rights to it, you have to also remember that Sonic is Sega's IP so as a working developer, it's a conflict of interest for me to make any Sonic related scripts available.
So bottom line, I have no intention to release it currently. I apologize if it's disappointing news, but there's plenty of other faces in the community (Mercury, Damizean etc) stepping up to the plate of creating 2D Sonic frameworks/engines
This post has been edited by The Taxman: 19 December 2012 - 08:09 AM