The Napoleonic Wars is very likely the single most enjoyable card-driven board wargame I've played. That sentence probably requires some parsing for this blog's audience, however.
The Napoleonic Wars is a board wargame; that is, it's played on a map with cardboard counters representing the actual forces involved in the conflict (and, in this case, actual generals, the quality of leadership being vitally important during the Napoleonic Wars -- not that it ever isn't, but it seems to have been particularly important in the period). As is typical of wargames, the rules are quite complex, much more so than the typical Eurostyle game -- though this game is not at the high end of the wargame spectrum.
It's also a card-driven game, sometimes abbreviated "CDG"; this means that players receive an allocation of cards each turn, cards are printed with a command point value, and players must play cards to generate command points to perform actions in the game. Typically, cards also contain "events" that affect play, but a player can use a card either as an event or for command points, but not both. Often, "events" can be used to affect the outcome of a particular combat, although they can have different effects as well.
Card-driven systems have two advantages over the round-robin turn systems ("IgoUgo") of most wargames. First, the use of command points means that the game can be structured to allow a player to make some moves, have another player interrupt, and so on -- creating something closer to the continuous action and reaction that is reality, rather than the strict sequencing of typical games. Second, the events are a means of adopting the virtues of an "exceptions game," a game in which some rules on components alter or interrupt the usual rules of the game, which allows for greater complexity without greater effort in learning the rules initially, and also far more variability of play. It does have the drawback, of course, that players are often, in a game sense, responsible for initiating events that in reality the position they represent had no control over. By way of example, the "Serbian Revolt" event might be played by the British player, but it is far likelier that a Serbian revolt would result from local grievances than from the actions of British agents, so there's a degree of ahistoricity here.
However, the reasons I like The Napoloenic Wars better than most CDG games have more to do with my personal predilections than with its superiority. I love the color and pageantry of the period; by contrast, the Civil War and World War II are much less appealing (to me). And I'm particularly drawn to diplomatic games. The Napoleonic Wars does an excellent job of dealing with the diplomatic situation of the era; one notable aspect is that you can by defeating a player in battle force him to submit, surrender some territory, and become your ally against his will -- a pretty fair representation of what France did to both Prussia and Austria at times. They may defy you later, of course, but they're your lackey for a time. There is also a pretty good system for handling minor and unplayed powers and their relationships with the players.
I like, too, the asymmetry of the game; each of the powers feels different to play. France is vastly powerful, and will win handily unless the others ally against it -- but becomes weaker over time, and particularly as the end-game approaches, it is likely that its opponents will fall out, since they each wish to win themselves. Britain is weak but safely across the Channel from France, and can win by husbanding resources and making a late-game play for territory. Austria is France's punching bag, but the Allies cannot succed without it; active Austrian diplomacy is vital (that is, whining for help). Prussia is weak but can win with control of only a few areas, and can play both sides against each other. Russia has the advantage of buffers between it an the French, but has to balance supporting the Allies and grabbing territory at its periphery, which is likely to piss its allies off.
One problem I have with the game is the way the rules are written. Not that they are written badly; the developer is Don Greenwood, and there's probably no one on the planet with more experience of rules writing. My problem is this: Any rules set has to do two things. It has to teach the game to new players, and it has to provide a comprehensive, complete reference where the players can quickly find the answer to any rules question that comes up in play. The problem is that these are often mutually incompatible goals. Teaching the game requires step-by-step instruction; providing a rules reference means grouping rules by mechanics and organizing them hierarchically. The rules to The Napoleonic Wars are excellent as a reference, but awkward as a tutorial -- and because they exhaustively nail down any possible dispute (this is a second edition, after all), they are far from an easy read. Moreover, they come across as describing a game that is considerably more complicated and difficult than this game actually is. As always, of course, it's best to learn the game from someone who has played before, but the problem is compounded here.
Despite this quibble, though, The Napoleonic Wars is an intelligently designed, somewhat chaotic, very colorful, and engaging exploration of 10 years of history in an evening's play, and quite a lot of fun to boot.