A healthy SubCritical runtime environment potentially has diverse code loaded and inter-linked. This makes licensing complicated.
Provisions are in place for a SubCritical game or package to specify, along a single axis, the "compatibility" level of its license. The points on this axis are as follows:
When writing packages, you are strongly encouraged to ensure that you make use of these provisions, so that a GPL'd game does not "taint" itself with proprietary packages, or a proprietary game is deprived of your GPL'd packages.
SubCritical will happily load a GPL package at the same time as an Incompatible package if the game's license is Compatible. This is by design. Package writers with non-Compatible licenses should ensure that they do not depend on cross-licensed code. It is my intention that this avoids any legal problems, but to be honest, I'm very annoyed that I have to deal with this in the first place.
Writers of new packages and games are strongly encouraged to use Compatible licenses such as the GNU LGPL, and avoid all this nonsense entirely.