Ahem - from the game description :
Successors was first published in 1995 by Avalon Hill. Some years later a second edition rulebook was published that gave more options for the Tyche cards. Successors III builds on the foundation of the Successors II rules set plus expansion cards that appeared in the Boardgamer. Minor refinements have been made to make the game easier to play and increase enjoyment. The map is very similar to the original with some minor changes around Macedonia. Counters have the same excellent artwork for the generals and new GMT artwork for the combat units and control markers. The Tyche cards have received the most changes—nearly every card has had some minor modifications and a few new cards have been added.
In addition to the changes, the rules have been cleaned up and improved. Years of questions and answers on Consimworld have been used to clarify the rules. The rules also include hints on strategy from a number a long-time Successors players, and an extended example of play.