Shadows of Greg is a fork of Gregic Additions, originally updated to work with modern versions of GregTech CE. This was necessary as Gregic Additions itself was abandoned, and the fixes included in GTCE meant not updating was impossible. GA is licensed under the LGPLv3, and SoG is licensed under the GPLv3. This modification and relicense is allowed by the terms of the LGPLv3 Section 2.
As of version 3.0.0, Shadows of Greg now depends on GregTech Nomifactory Edition. Older versions depend on GregTech Community Edition.
Worlds created with GregTech Community Edition and Shadows of Greg 2.20.4 may be updated to GregTech Nomifactory Edition and Shadows of Greg 3.0.0+. Please refer to the changelogs of both projects to know what changes to expect.
SoG contains all features in GA that were not added directly to GregTech.
Any content not listed here that was previously in GA has likely been implemented in GTCE, and is not in SoG.
As of SoG 2.10.0, the addon GTCEBees has been merged with SoG.