I'm the person who moved it, Monte. It was a toss-up between Rules and the d20 forum, and with threads for a specific OGL game we lean more towards the latter. General Discussion was certainly the wrong place for it.
We actually had a long discussion about where AU threads belong back before your game first came out a year and a half ago. Whether or not AU is compatible with D&D (and it clearly is - I was just borrowing an AU class yesterday for my game), the hard line we draw for where a particular game's threads belong is how that game describes itself. Is it a product for D&D? If so, General Discussion. Is it a d20 game (Grim Tales) or OGL game (Monte Cook's Arcana Unearthed)? Then it goes in the d20/OGL forum. This gives us a consistent, clear and easy division. We're certainly not trying to hide it; AU is the first example game listed on the forum's description.
If non-d20 games had more traffic here, we'd probably have a separate forum for them as well, but a lot of that traffic ends up at rpg.net.
So you're not alone in thinking it's odd that a game as close to D&D belongs in the OGL forum. Since the game is specifically OGL, though, that's where it goes. I suppose that's an accidental tradeoff for the benefits of getting to include character generation rules.
I'm not trying to be a jerk about this, but I do want to be clear about why we have the categories set up this way. If you have any questions, let me know.
- Kevin