It is so 'overhauled' that there is no real relationship between the Runequest game and the Hero Wars game except for the setting of Glorantha. Runequest was the original Percentile Based and Skill Based rule set and ushered in an era of Simulationist RPGs.
Hero Wars uses a system that essentially involves players "betting" on the results of conflicts via an abstract system.
The first edition core books were riddled with errors as this book was rushed in order to avoid its publishing company from going bust.
As of Mid 2002 the line has expanded to A players book containing the core rules. A narrators book which contains the rest of the rules. A book listing all sorts of creatures and people. A book describing the Orlanthi setting for players and refs.