I can't find a good source on the release date of this website.
The earliest external resource referencing Sheppard Software is from November 23rd, 2005 ().
However, Google lists the website as being from May 28th, 2005 (). I've set this as the release date.
In case anyone can dig up anything else, please feel free to go ahead and update the information (or request an update).
http://www.sheppardsoftware.com/about.htm
It doesn't have a date for the site though...
https://web.archive.org/web/19981111190739/http://www.sheppardsoftware.com:80/
There's a web archive from November 11th, 1998 of the site if that helps at all
Alright, so the earliest instance of a flash-based geography web game with maps, on the Wayback Machine, is July 25th 2002 (https://web.archive.org/web/20020725104705/http://www.sheppardsoftware.com:80/), with the "States Web Games". It seems to be similar enough to the current games.
I'll make that the "release date" and we can just consider updates and improvements as newer versions of the same game, if that's cool with everyone. I'm open to suggestions, though