It would be nice to have a list of Panzer Grenadier products by release date, or an option of seeing the Library listing of games displayed in Chronological Order.
Did you know that years before PG-HQ there was a geeklist trying, largely in vain, to sort out all the cross-compatibilities within the PG universe?
I applaud your ability to find something we've overlooked. It seems the closest we have to a chronological order is the top of the Developers page:
http://www.pg-hq.com/library.php?type=catalog&id=humans
Maybe a simple Game Search would be worth adding...