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Missile Variant for DiskWars (a la RangeWars)

by Don Lynch

And now for something completely different - a return to the missile topic.

Some mention was made a while back in this thread to convert the Rangewars hit system to Diskwars. That is, to have a 50% chance to hit with each missile, but only on the nominated target with no friendly fire possible.

The RW system allows people who do not personally have the missile drop skill to equalize somewhat in their chances. It replaces random placement with the laws of probability. It ignores such things as base size of target and exposed size of target. Well, these things can be accounted for in some logical ways.

First some numbers. The following chart is the relationship of the diameter of the standard disk sizes in inches to their respective areas in inches. Applying the standard formula of pi*(radius squared), we get:

Size Area
1.75 - 2.41
2.00 - 3.14
2.50 - 4.91
3.50 - 9.62
*4.10 - 13.20 (*Approximate size)

Having played around with these numbers, I didn't like the results. I felt the original arithmetic ratio for the disk sizes was better for gaming purposes. Being a believer in design for effect and knowing where I wanted to end up (around 50%, skipping the square part of the formula), the following table is the result:

Size Area
1.75 - 2.75
2.00 - 3.14
2.50 - 3.93
3.50 - 5.49
*4.10 - 6.44 (*Approximate size)

If we view the area of the disk as the main factor in hitting, there is an immediate graduated relationship among them. Most simply and accurately, one can use the figures 27%, 31%, 39%, 55%, and 64% as the
possibility of hitting a disk depending on its size. Presuming a dice based resolution, this requires using percentile dice for each hit. This is a bit time consuming and unrewarding for my taste.

Let's try a D20. The possiblility of a hit would be less than or equal to 5, 6, 8, 11, and 13. This is much better as multiple D20's can be rolled at once and immediate results read quickly. And D20's are plentiful due to the popularity of D20 based role-playing systems. (Or is that roll-playing?)

What if you only have D10's? Well 3, 3, 4, 5, and 6 will work also, at somewhat less accuracy.

If you have only D6's, you could try rolling a single die per missile for 2, 2, 3, 4, and 4 as hits. Rolling pairs works better for 5, 5, 6, 7, and 8 respectively. (28%, 28%, 42%, 58%, 72% chances by the numbers.) This again implies a separate roll per hit, as per the percentage thing, but it does work surprisingly well.

So my default favorite is D20's. Let's use these for the rest of the discussion.

There are three main issues left. Base chance of success, targeting units in melee, and friendly fire.

I am going to ride roughshod all over the base chance of success issue. Which is, if the 50% chance of a hit is the standard in RW, doesn't the average chance of a hit fall off when shooting at smaller targets? That is, the 1.75 and 2.00 sizes. The answer is yes, of course. Well so what. (I'm going to average the 2.50 with the 3.50+ sizes as a wash.) Given that many DW armies may be made up of many 2.00" disks, the chance of being hit is reduced from 50% to 30% for these units. That only matters if you accept the 50% as infallable, immutable, and the desired objective. I don't, it ain't, and the objective is targeting by size. If these numbers don't work for some players, add +1 to all chances of success and try that (6, 7, 9, 12, and 14). The same +1 to all chances of success can be used for larger missiles such as boulders.

Random targeting will be covered in the next two items. I will use some creative thinking for random targeting. Who said it has to happen? It is an interesting feature of DW. But is it more trouble than it's worth? Personally I like it, but remember that while DW offers some bonuses in this regard, it also takes a lot away.

Consider what happens when units are engaged in melee. One unit covers some or all of the other unit. Unless we're talking a large dragon flying over its prey at the instant of all the shots landing, it doesn't really work that way. What we really have is two plus units intermingled in melee. Or as Patrick McGoohan said in "Braveheart" when questioned about shooting into a crowd, "We have reserves. They don't. (pause) Archers!" So a simple rule is when shooting at a disk in a combat stack, count the number of units in the combat stack. Choose the right die type, assign a number to each unit, and roll to see which disk(s) are
the targets. This will require an extra die roll per missile. For example, there are three units in melee. Choose a D6. Assign 1 and 2 to one unit, 3 and 4 to the next unit, and 5 and 6 to the last unit. Roll as many (D6's) as there are missles. Then resolve a shot against each resulting target as if that target were the original target. That is, use a D20 versus the size of the resulting target. This does it take into account (on purpose) how much of a given disk is exposed to fire or blocked by disks above it. Note that disks that can't see the sun can still be hit. This also does not take into account the relative size of the possible targets when dividing the shots among the meleeing units. It can be done, but for me it is way too much buck for too little bang.

As for random or friendly fire, I will first quote from above, "Who said it has to happen? It is an interesting feature of DW. But is it more trouble than it's worth? Personally I like it, but remember that while DW offers some bonuses in this regard, it also takes a lot away." The easiest way to address this issue is to assign a number to the possiblility of random fire. This number is part of the original attack roll and must be part of the 'miss' result. Let's just say that 18+ is this number. On any attack rolls of 18+, some sort of random fire occurs. The hard part is picking the new target. I would propose getting a measurement of all units within 6" of the original target. For simplicity, treat each combat stack as a separate unit/target. As with multiple melee targets, choose the right die type, assign a number to each unit, and roll to see which unit(s) are the targets. If the original target is in a melee, do not consider any units in that combat stack for this re-targeting, as it is done as part of the melee targeting. Determine the new target randomly and resolve as usual with a D20 versus size of target. Subtract 1 from the base chance of success for each complete inch that the new target is distant from the original target. In all cases of random fire, only the roll against the original target is considered for random fire. Any 18+ rolls attacking random targets is simply considered a miss, not a new random fire.

Nowhere is the possibility of a missile hitting multiple adjacent disks now covered. Who cares?

Much of this can be retrofitted to Rangewars and L5Rdw also if desired. For simplicity, consider ignoring random fire. For more simplicity, consider that only the top disk in a combat stack (or any unpinned disks in a compound combat stack) may be targeted.

Hopefully this all makes some sense.

Don Lynch