If you’re referring to this board section…
http://www.harrisgamedesign.com/phpBB3/viewforum.php?f=14&sid=b4ef393ddbe64b388ee7fb9bd5a2cedc
…as far as I can tell it was set up by Larry in October 2004 under the very general theme of “What are some MUST HAVE’S you like to see in an advanced game?” When someone on the board asked “What is this anyway? Is advanced axis and allies really being designed, and if so, about what percent is it done? Would we be able to expect to see this this year? Next? 2007?”, someone called Lobo answered “It’s something that Larry is interested in doing. It may or may not see fruition.” Larry confirmed this by saying “Lobo is correct. There are no definitive plans or time line for such a game. There is however an identified need for this baby.” So the board section seems to have been just intended for brainstorming purposes, not for the development of a specific game.
Just to put those threads into context: October 2004 is a few months after Revised and D-Day came out, four years before Anniversary came out, and five years before the first 1940 game (Pacific 1940 1st ed.) came out. So this notional “Advanced A&A” may in fact have generated some ideas that were incorporated into some of the A&A games that were published since 2004.
