One day, H.G. Wells fell in love with what seems to be a miniature firing cannon made for toy soldier, and with the help of his friends, made an entire wargame around it. This is probably the first formal wargame for non-soldiers of its kind, and it's amazing how little both the mindset of creating a game and playing it has changed.
Wells talks about the process of balancing the game through playtests, formalizing rules, adding different objectives to change player behavior, and introducing variant rules for more players, as well as a more sim-like approach for use as a replacement for the military exercise Kriegsbell. It's startlingly modern, and wargamers haven't changed one bit since the days of Little Wars, except to add more complexity to games. The first two chapters detail the game creation, and they are as fascinating as the creation of modern games is. Then, there is a list of the ruleset, some variant styles of play, and a slightly out-of-place hope that the nations of the world would forsake big wars in exchange for the little wars he made.
If you've ever played or created games, this is an excellent read in both a historical and design sense. Even the practical problems matter; one thing he did was to outline all the building positions in chalk so that if a house was moved during play accidentally it could be replaced. I'd rate it five stars if not for some problems.
One problem is that it's simply too niche to be amazing. It's mostly rules and minutia, and non-gaming geeks won't see much to it. The second thing is that the free versions have no illustrations included, so if this really interests you, spring for the paid one. Beyond that though, it's an interesting and enlightening read. Gaming geeks 120 years ago aren't that different from today's geeks.