Paul Leniston offers a set of free wargames rules for Napoleonics. He and his gamer wife have been playing and testing them for many years.
napoleonics
Napoleonic DBA Rules
Steve Burt has a set of free wargames rules for playing Napoleonics using DBA mechanics.
Resolve Napoleonic Rules
Resolve is a set of free wargames rules for Napoleonic warfare.
Simple Sails Rules
Simple Sails is a set of free wargames rules for Napoleonic fighting sail.
If We Could All Be Napoleon
If We Could All Be Napoleon is a set of free wargames rules for 15mm Napoleonics