I've readily admitted that I am not now nor have I ever been a wargamer in any meaningful sense. With the exception of some microgames and a handful of "bookshelf games," I simply lack the gene for wargaming. Or it may simply be that I'm not very good at most wargames. I lack both the patience and strategic-level thought needed for such diversions, which probably explains my limited direct experience with most of them.
There's one significant exception, though, and that's Diplomacy. Of course, some might balk at the notion of calling Diplomacy a "wargame" and there's some justification in this. Diplomacy lacks most of the characteristics of the traditional hex-and-chit wargame. Its map, for example, is divided into seventy-five land and sea regions of varying sizes and movement between them is abstract, as is its combat system. Likewise, combat makes no use of a result table. Indeed, random outcomes of any kind are wholly absent from Diplomacy, since the game doesn't require dice to play. Everything that takes place within the game takes place because of specific decisions made by its players and it's for this reason that Diplomacy is, in my opinion, one of the greatest games ever made.
Designed by Allan B. Calhamer, Diplomacy made its original appearance in 1959, gaining a large following, including many people later associated with the roleplaying hobby, such as Gary Gygax and Len Lakofka. I personally never saw the original version of the game, having been introduced to Diplomacy through the 1976 Avalon Hill edition whose cover art I've included above. Diplomacy was one of those games that everyone involved in the hobby in my area played; it was part of the "background noise" of my gaming in the late 70s and early 80s. Because the game requires a minimum of five players and works best with a full seven, it wasn't a pickup game. You needed to work hard to get a game going, but it was usually worth the effort and there was no shortage of people interested in playing. In high school, I played a lot of Diplomacy with my friends and we'd often gather at one another's houses on the weekends specifically to do so. In college, my roommate ran a slow-motion one-move-per-week Diplomacy game with some of our friends and it was a lot of fun too.
The genius of this game are its simple concept and rules. Each player controls one of the Great Powers of pre-World War I Europe: Austria-Hungary, Britain, France, Germany, Italy, Russia, or Turkey. Each Great Power controls several regions on the map, some of which are designated "supply centers." For every supply center a player controls, he may build either an army or a fleet with which to conquer more territory (and thus gain more supply centers). If a player loses control of a region with a supply center and, at the end of his turn, has more military units in play than he has supply centers, he must disband any excess units. Outright victory comes when a player acquires 18 or more centers, though many games end in draws, as two (or occasionally more) players decide the game has dragged on long enough without any clear winner.
As noted, there are no dice in Diplomacy. Everything that occurs does so because a player chooses to make it happen. However, especially in the early stages of the game, most actions require the assistance of other players for success and therein lies the essence of the game. In between turns, players are expected to negotiate with other players for support in their own plans. Thus, treaties and alliances are not only commonplace but expected play elements. Of course, so are betrayals, as no one is required to abide by the terms of anything to which they agree, though players with a reputation for treachery soon find themselves popular targets of others' ire. Consequently, good Diplomacy games are a conflict between the need for others and naked self-interest, which creates a terrific dynamic.
It's easy to see why so many early roleplayers were involved with Diplomacy -- it's practically a roleplaying game itself. Goodness knows my friends and I treated it that way on more than a few occasions, penning our orders in elaborate fashions as if they'd been written by ministers in service to fanciful European monarchs. Silly though this was, it added considerably to our fun and I suspect it helped to lighten the mood of the game, which, as anyone who's ever played can tell you, can sometimes turn quite cutthroat.
I haven't played Diplomacy in many years, but I'd like to. The problem is finding six others with whom to do it and the time to set aside for it. As I understand it, the game is still published by Wizards of the Coast as part of its Avalon Hill brand and I appreciate that. The game is also avidly played by mail, which I find delightful, and on the Internet, thanks to the simple nature of its rules and its emphasis on human interaction as the driver of its events. To my mind, that remains the real genius of Diplomacy: its emphasis on human interaction and player skill, two traits old school roleplaying games have in common with it.