The game itself has a cult following. In contrast to the typical hexmap tactical war games sold by AH during the day, Kingmaker touts a simplified movement and combat system, and most of the play is "in the open" so it's relatively easy for new players to pick up. Furthermore, success in game play depends much more heavily on interactions between players than on tactical skills, so again new players often manage to hold their own. The game is best played with as many players as possible (five to seven if you can manage it) -- all players stay in the game until the end, and even a player who has been very weak for much of the game can play a decisive role in the end-game. Plagues, revolts, and the occasional summons to Parliament add elements of chance that are likely to disrupt long-laid plans and reallocate power. Usually if one player gains the advantage, a coordinated alliance by most of the other players can bring the leader down -- provided they can hold together without backstabbing. So the one issue with Kingmaker is that if played by the rules as given, the game can drag on. Specifically, as written, the rules provide no mechanism for a weaker force to defeat a stronger one, so the end-game is generally won by defense instead of offense. The usual trick is to pile all of one's forces onto one square (so called "turtling") and then waiting it out.
I enjoy playing Kingmaker but I can't play all night. Over the past year or so, I've evolved a set of modified "House Rules" specifically designed to speed things up so that a game can be completed from first move to end game within four hours. The main change is to shift the battle rules much more in favor of offense than defense. This means that stronger players cannot afford to just sit back but must press the attack. Battles are more deadly, and power shifts quickly so players need to strike while they can. I've also chosen to clarify a few ambiguous issues and I've added a few "fun features" (e.g., parliament can vote to declare a king to be illegitimate) enough so that anyone who arrives to my version of the game will find the play slightly different from what they may be used to.
These are PDF files. These rules assume you already have your own copy of the game and have a copy of the the original rules from Avalon Hill. House Rules variants are typically indicated by text navy blue: Many rules blatantly stolen from http://www.maximumawesome.com/articles/kingmaker.htm and several other sources -- really many sources -- too numerous to mention. I'm always tweaking these. When I play with many friends or at a con, I usually like to serve only as the GM, not a player, so that I can give advice and lay out the options (and potential consequences) for less experienced players.
Here's the table-of-contents (image grab:):
A few useful things I have custom-made, feel free to use:
-Corbin Covault, February 2017. Look for future updates. If you have comments or suggestions email mail me at firstname.lastname@example.org and be sure to put the word "Kingmaker" in the subject header.