Black Powder is a set of free wargames rules by Wes Rogers for skirmish warfare in the period 1600 – 1870.
King George Commands and We Obey is a set of free wargames rules for American War of Independence, Napoleonic Peninsular and the American War of 1812. The author writes:
My key requirements are:
I spend a large amount of time and money collecting units. I decided I wanted them to stay on the table long enough for people to see, therefore no casualty removal.
I hate the “my turn/your turn” approach. With that in mind I use a card based turn system. I first used this in my Dad’s army game. Depending upon the level of game you are playing, a playing card is allocated to each unit or in larger games brigade commanders and above. This also means turns are not all the same as an end of turn card can come up at any time.
They have to be easy to learn. The common approach should assist with this and it is then just about the era specifics.
As little paperwork as possible. Most units have a small tab on a base. This contains all the information you need so no other paperwork, in most cases. This could of course be kept separately rather than attached but I think in a demo game it also allows visitors to see which units are representing which.
Enjoyable. I am not too serious and enjoy a light hearted approach at times to rules. Have a look at my rocket rules. While they may be a little slow to enact, imagine the gasps as rockets snake across the field. You never really know where they will end up!
Bravado is a set of free wargames rules for the horse and musket period. There are guidelines for both the American War of Independence and Napoleonic Wars for play. The rules employ an interesting mechanism where the players compete for initiative, deciding how much they will risk disaster in order to have another phase of movement or attack or time to reform their regiments.
Steve Burt offers a set of Napoleonic Wargames rules.
In the Name of Glory is a commercial set of Napoleonic Rules that now is available as a pdf download. I have a hard copy of the rules and like them very much.