eRules is a set of free wargames rules for the Napoleonic era. From the introduction:
eRules Napoleonic.txt is a set of rules for the Napoleonic wars designed by WargameSystems following the same principles as eRules World War II, except that Napoleonic.txt is provided free as a draft document for you to download, try out and contribute to. Let us have your suggestions for adding to it or improving it.