I've always been fond of the period but wanted a set of rules that put the emphasis on maneuver, fatigue and command. So I set about making my own. "Taisho", tries to borrow from what I like about existing rule sets while mingling a few of my own ideas in along the way.
For me designing rules is like going on holiday. You work out the destinations you want to get to and then manufacturer a plan to get there. So I start at the end result I want to achieve and work backwards to get there. Sounds like a good plan.
The armies are quite generic. You basically have both armies fielding Samurai as their elite soldiers while bulking out their army with Ashigaru. I wanted to simplify any combat by having each unit having between one to twelve bases. Ashigaru units would be larger and have either three of four figures per base, While Samurai smaller and between two, (Cavalry) or three, (Infantry) figures per base. Elite units, Commanders and Champions would tend to field much smaller base numbers. I wanted to have the feel of a Skirmish game with the tactics of a mid sized battle. Luckily the period has small battles at its beginning to massive armies at its peak. These rules are aimed to cover the earlier period before mass alliances and famous Damiyo's dominated the countryside.
So the basis of the combat revolves around the front ranks of formations dicing off. Aiming to get the highest single die result on either two "Red dice" for Ashiguru or three "Red dice" for Samurai. So if you have a frontage of four stands of Ashigaru fighting a similar frontage of Samurai I was aiming for one draw, one loss to Samurai and two losses to the poorer Ashigaru.
For the sake of comparison the Ashigaru two, (Red dice) have been coloured white and the corresponding table blue. While the Samurai three, (Red dice) are indicated in the yellow table. The percentage chance of getting a particular highest dice are calculated above. The results are then applied to the table below to work out the ratio of casualties if the above combat eventuated.
The top table above calculates the Ashigaru winning 28% of the time, Losing 47% of the time with the remaining draws accounting for 24%. So close to the one win, two loss and one draw target.
So while both sides throw a set amount of "Red dice", which accounts for the relative strengths of the combatants they then supplement this throw with additional white dice which are used for fine tuning any modifiers. These "White dice" modify the Red result by one for each white six result.
The second table above gives the average result if six white modifier dice were added to the Ashigaru attack. In reality they are likely only to have a fraction of these "white modifier" dice but if one of those dice turns up a six the likelihood of a win goes into the Ashigaru's favour.
The last table shows the benefit of having six, "white modifier" dice being added to the Samurai throw. Again they are unlikely to have this many. But if they do end up with an addition one being added to their, "Red dice" throw the balance is very much in their favour.
The idea is to keep the, "dice off" nice and simple but to allow for incremental changes with the modifiers added. This allows a Paper, Sissors Rock approach where the different weapons the units employ to have advantages and disadvantages dependent the situation, terrain they find themselves in.
To demonstrate how the modify dice work I've used some great little icons from a boardgame called "Age of War". A simple game but cheap and quite a lot of fun,
The Units are from Civ II Mods units, https://www.youtube.com/watch?v=rBnnqR_5pkQ
Fairline's and the moding team work is massive. And if you are wanting some icons to use on a private project all periods are covered in such small detail.
So while the armor differences are covered by each sides, "Red Dice" smaller modifications are covered below for the extra, "White Dice" These white dice modify the Red result by one for ever six thrown.
So the modification dice basically follow the above principals. So in the example above the Cavalry would kill on average say two Ashigaru for every one Yari Cavalry lost. But more than double that against a similar Ashigaru Arquibusier who hasn't the means to defend himself.