Is all “d20” discussion on-topic here?
All 3rd ed. D&D is d20, but not all d20 is 3e D&D. This newsgroup is specifically for discussion of D&D. Thus, some d20 discussion is appropriate for this newsgroup, but not all d20 discussion is appropriate for this newsgroup. The exact position of the line between on-topic and off-topic for d20 discussions is in about the same place it is for every topic that is discussed on this newsgroup, from history to movies to religion to alignment to guns to politics to other RPGs. By and large, that means that if the discussion is about how to take elements from other d20 games and integrate them into D&D, then that is on topic; if the discussion is about other d20 games in their own right, without any meaningful references to D&D, then that is off-topic. For most non-D&D d20 discussion, see rec.games.frp.misc or rec.games.frp.moderated.