On a whim I bought Kamakura in the 80s from a game store. The box is completely blank on the back, and the front's description is only "A Game of War, Diplomacy and Machiavellian intrigue." Being a teenaged boy, the cover art of samurai slashing with their swords made me think it was a different kind of war game. The cover didn't even indicate it was a multiplayer game (though a more mature player would probably know it from the word diplomacy).

It turned out the game had nothing to do with feudal lords or samurai, really, rather it was a strategic depiction of Japan during the Kamakura shogunate in the 12th-14th century. There are two games:

One is a game based on the conflict between the Minamoto clan and the Taira clan, which ended with the Minamoto unifying Japan (centuries prior to Tokagawa's feat). Other prominate clans in the same time period include the Fujiwara, Hojo, and Ashikaga (misspelled as Ashikago in this game).

The second is a two player scenario where Kublai Khan's mongols invade Japan from Korea.

The game is played like Diplomacy. There are 69 provinces in the game, 44 are yellow and known as shoen, or your supply centers. 15 of them are the starting location of the five clans mentioned above. A an extra player can play as the shoei, or warrior monk clan, and start in any three shonen. Or they can play as a random clan that players take control of on alternating turns.

The winner of the game is the player that controls 22 shoen.

Components:

The components are a sheet of double sided black and white counters on different colors, which are nice enough.

The map is a paper map the 16" x 22", and is a map of Japan, with Hokkaido cut off. The map looks good, has useful information, but some of the provinces smaller than a counter. It's probably 1/3 too small for the game.

Rules:

The rules are essentially the same as Diplomacy. You negotiate, then write out orders. You resolve combat, where you compare supports and attacking armies vs. supports and defending armies. Some differences from Diplomacy: there are no permanent naval units, any army unit can convert to a navy unit when it goes to sea. Second, units can be double strength in a province. There is a new order for unite and separate. Third, there are garrisons (single armies) on each unoccupied supply center or shoen. This makes reaching the 22 shoen mark slower than in Diplomacy, where all neutrals are easily occupied. This appears to be for balance purposes, as historically the Taira are the sole clan to the south and could have a run at 12 shoen adjacent to their starting area.

Despite this the game balance is nowhere near that of Diplomacy. The Taira have the easiest route, whereas Minamoto, Fujiwara, Tojo and Ashikaga are all close to each other. Woe to the Ashikaga who are adjacent to zero shoen other than those already owned by the Hojo. It's a very bad situation for the Ashikaga.

There are some optional rules for typhoon, famine and earthquakes, which have the effect of destroying units in the randomly selected area.


So, an intriguing alternate location to Diplomacy, but perhaps too wedded to historical situation for balance. There are too many supply centers, 10 more than in Diplomacy, and 14 more neutral ones (since there is one less player in the game). A good balancing idea will be to eliminate the southern most islands (9 shoen) and keep the game on Honshu and Hokkaido, so Taira do not run away with the game, and to play the shoei monks right next to the Taira clan. I would also redraw the Kotsuke provence to border Ashikago's Shimosa.

One important thing missing from this setup is a conference map. Without a conference map, and with so many unfamiliar provinces, it's impossible to plan moves with players without being in front of the map. I am going to try to create a conference map for the very few people who own this game.

Two player games
The game also accommodates 2-3 players, unlike diplomacy. One two player scenario is all the armies of Japan against a Mongol invasion. The Mongols have 41 double strength armies which convert two single strength fleets, the Japanese have 45 single strength armies which convert to double strength fleets. There are also typhoons in the game. I'm not sure this scenario makes that much sense.

Two players can also play as the Taira/Ashikaga and the Minamoto/Hojo. Three players play as Fujiwara, Minamoto and Taira clans.

Conclusion
A good complement for a Diplomacy lover (not sure how they got away with this game without being sued), but not a replacement, and will require tweaking for balancing. It's a shame it didn't catch on more, as its PBEM potential is great.