Warflag has some modifications for the commercial Age of Reason rules to allow you tu use them to fight battles in the Age of Marlborough.
Corporal John is a set of free wargames rules for the Age of Marlborough. The author writes that:
The set can be used, not only for Marlborough’s wars, but for those of Charles XII, Peter the Great, Louis XIV and even Gustavus Adolphus.
The rules are fast-play but still retain the detail to give the correct flavour of the period. They will handle games of thirty or forty units per side or much smaller games with a handful of units.
Lilibulero (.zip file direct download) is a set of free wargames rules for wargames in the 1600 to 1700. The author writes:
These rules are shamelessly adapted from the old Wargames Holiday Centre “Marlburian Rules” written by Mike Ingham, with chunks lifted from Barry Hilton’s “Under the Lilly Banners”, produced by the League of Augsburg. Barry’s set was in turn based on Mike Ingham’s original. Another variant of Mike Ingham’s rules is “A Grim Panoply”, written by Phil Olley, and I have to admit I’ve also raided Phil’s rules for ideas. The orders section was adapted from Pete Berry’s English Civil War set “Forlorn Hope”. If imitation is the sincerest form of flattery, then these three guys should be delighted!
Angus Konstam, 2006