The name change is done for two reasons: The old name (at least the acronym) was a bit obscure, and the new name is catchier. But the main reason is the database contains information about games from other platforms than Amiga. So the old name wasn’t really fitting any more. The openretro.org site has been up for a good while now, and starting today, all oagd.net links are automatically redirected to openretro.org.