SonicGDK (short for 3D Sonic Games Development Kit) is an impressive Unreal Development Kit powered Sonic The Hedgehog game creation tool which allows users to create some seriously impressive Sonic games (much better than the tat SEGA have been making lately anyway!)
SonicGDK gives you access to 3 versions of Sonic (Classic, Generic & Modern) with super forms, power-ups, badniks, special moves, controller support, checkpoints, bumpers, spikes and various other traps – basically everything you need to make a Sonic game.
IMPORTANT NOTES FOR INSTALLING SonicGDK:
1. Download the latest version of SonicGDK HERE
2. Visit www.unrealengine.com/udk and download the “JULY 2013 UDK BETA” release.
3. Execute the downloaded .exe file and follow the instructions (choose UT3-derived game project, ignore Perforce options).
4. After the installation process, close the UDK Editor if it’s opened.
5. Copy the SonicGDK’s folders Development and UDKGame and the .bat files to the UDK directory.
6. Run the Unreal Frontend tool (\Binaries\UnrealFrontend.exe), click on the “Script” button and choose the “Full recompile” option from the list.
7. Close the Unreal Frontend tool; installation is complete.
8. Run the game or the editor through the .bat files. The first time that you open the test map, it will compile all the material shaders and take a really long time.
You’ll find more info on SonicGDK on IndieDB HERE and the Wiki page HERE