Most will be aware that the reason GW games used a D6 was that this is more common, and cheaper, than other dice. Their flagship games were conceived of a one die per model and the handfuls of dice this could lead to made other polyhedrons uneconomic. Though they made the decision when the model count of their games was much lower, I think it was vindicated by the number of games that used it (it's obviously not 'broken') and in what it allowed. My favourite GW game is War of the Ring, and the choice to go d6s was was perfect there. I remember facing Martin's goblin hordes, at a 1000pt tournament, and having him fill a beer glass up with the smaller size of d6, before rolling them all out. Very thematic. But I've drifted from one model per die in an effort to speed up play.... So what if the Book of War was reimagined as a d10 game?
Firstly, I'm not sure anyone reads these. But for the benefit of the two other people on the internet that like reading home-brew rules tinkering: The Book of War has a roll to damage (modified by the second value of your Might Characteristic), where you hit by rolling equal or under your opponents Toughness. The Might of a Human with Greatsword would be expressed as something like 6/+1 and the Toughness of a Magden Brave would be expressed as 6/3. The First value is the roll to cause a stress and the second causes both a stress, and a casualty. The +1 on the Greatsword's Might value raises both the enemy Toughness value by one. So a Greatsword unit would roll a number of D10s, hitting on 7s and causing a casualty on 4s.
The game works by grouping models in ranks of five. If they were on 20mm wide bases, this gives a frontage of 100mm, and if on 25mm bases, the frontage would be 125mm. A unit always gets to use its full dice if fighting one on one. If it has contacted multiple units, then it can split dice, but can only allocate as many dice per rank, as it has models touching its target.
Using a d6, the process to get a spread of outcomes could be a little more convoluted than I like. I think d10s can be used in a way that makes intuitive sense. Stats should still be grouped near the middle of the range but something like a +1 becomes less impactful. This means I don't always have to put in all the other steps I've been using to modify them. In particular, I think almost every thing, including weapons, can be expressed in the characteristics and always using the same logic. Then only special cases (eg Vulnerability to fire) or the addition of missile weapon range, would need to go in an abilities or special.
This is pretty important in a Fantasy game, where you need to model Dragons against a peasant. If you don't have rerolls, then you get the situation where 1s have to always fail and 6s always succeed and then the spread is only 1-5. I still think I will end up with rerolls but no longer will they be a constant feature. Not needed to model the peasant but perhaps needed for the ones that are starving...
The obvious benefit is in modelling more and less skilled units. I can make each rank of five models worth 2 dice. If the combatants are of equal skill (the first part of their Might value) then both can add one die. If one side has a point more Might, it may add the die but it's opponent may not. Then for each point more Might, another die per rank may be added.
Here the balance and differences between formations shows well. Loose order just don't get ranks at all. This means they can use skill to prevent enemy gaining extra attacks or to get a slight edge themselves. But that is all, armies fight in formation for a reason. Close order foot get to count as if they have an additional rank for stress but not for determining attacks. They only fight in more than two ranks when using specific weapons like Long Spears.
This means that when they have equal Might, light foot warbands can do more damage as long as they have the numbers joining the fight. They fight by crashing into the enemy line, leaping over front ranks, and clearing spaces with wide axe-blows. This line-breaking style means they get to use two dice per up to three ranks. If they are more skilled, this edge can become devastating and they can cut through their enemy getting the bonus dice for higher Might on three ranks. Better yet, they have a higher speed so do these hits before their opponents.
But what if the close order foot are more skilled? Let's assume we are looking at two units of 20 warriors, four ranks deep. In a situation where they have one point more Might, They will get +1 attack dice, and 2 per two ranks, so a total of five. Their Light Foot opponents get six. If they two more points of might, then suddenly it's on. They get +1 attack dice and 3 per two ranks so a total of seven. In my mind, this is Caesar's Legions vs Gallic Warbands..... Or Magden hitting a Varangyr shieldwall.
Or how about Single Combats? We can just have a combination of a dice pool and the above system. Both combatants could get two dice, Then bonus dice as above (ie 1 each if even, or 1 for each one point better). Unlike in unit vs unit combat, successes are cancelled off against each other. The faster combatant (higher Speed) gets to make one unopposed attack per point of Speed advantage. Of course, if the faster combatant got less successes, they will probably be using these by furiously blocking.
Shooting can work in the same way. Instead of comparing your Might to your opponent's, you compare to the difficulty of the shot. A shooting unit gets two dice per rank shooting.The difficulty of the shot is usually 2. If the unit has more than two ranks, then the difficulty starts at 1. Then you need to see how hard the shot is. +1 for being over effective range, +1 for shooter moving +1 for light cover and and additional +1 for heavy cover +1 for weather. (The hardest shot is a 7.) Just like in melee, the shooter gets one bonus die if it matches the difficulty of the shot or +1 bonus dice for each point it exceeds it by.
This has the effect that all units throw a few shooting dice. However, as the shot gets harder, only the more skilled shooters are able to get bonus dice. Everyone else is at the level of a less skilled archer. A typical unit of bow would have a Might of 3 or 4. If shooting at a big target, close by, they aren't too bad but it falls away quickly. It is the uncanny archers, like the Poisonwood Fey, who can really pile on the shooting dice and land plenty of hits. However, at long range, on the move, in the sleet, they are no better than a human at getting enough hits on some men bunkered down in ruins.
That's enough words for now. I should work this back into the stat lines for two lists and give it a try.