BMDev 3: Keywords

Resolving the tension between consistency and variety

From a practical standpoint, the BMD attack resolution design is one of the most important to get right. It has to be fast and fluid, and it has to be sensible enough that common questions have an intuitive answer.

We’ve already seen the basic attack resolution design covered extensively, including past mistakes and present successes, with very little detail left out. But the implied setting of BMD, a far-future human vs. alien total war, demands an extensive array of weaponry. Can our resolution system really handle the huge variety of weapons brought to bear in this conflict?

Yes, and a big part of that is the system of keywords. Let’s take a detailed look, starting from the beginning, at attack resolutions enhanced by the keyword system.

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Attack Anatomy

With some minor simplification, making an attack involves the following steps:

1. Accuracy Step: Each attacking figure rolls P1 +Accuracy. Each figure that was successful contributes their attacking attributes, including their Coverage.

2. Lethality Step: Add up the total Coverage. Roll P[Coverage] +Lethality. Every success is 1 Damage.

3. Defense Step: Add up the total Damage; this is the Damage Pool. The defender resolves the Damage Pool.

As a quick terminology reminder: PX +Y is a dice pool of size X using Y as a bonus, always looking for results of 10 or higher. P12 +3 indicates rolling 12d10 and looking for the individual dice that read ‘7’ or higher (7+).

Attacker and Defender

We have a unit of Terran soldiers (the attacker) targeting a unit of alien scum (the defender).

Let’s look at relevant equipment. The Terrans are all using the ESA G3 Laser Rifle.

Name         |ACC Bonus   |COV  |LTH  |Range  |Special
ESA G3-LR    |   +0       | 4   | 3   | 12"   | none

This laser rifle is old Earth Sectors Authority equipment that became worthless surplus after the ESA was convinced to dissolve its police and military presence in favor of alien enforcement programs. This kind of equipment can be found in great supply almost anywhere that has (or once had) Terran presence.

Their targets are Vessamar light infantry wearing their standard Calibrated Thermal/Hardened Suit.

Name         |PRT   |Special
Cathardes    | 3    | none

This protective suit is made for an inhumanly slender, winged creature. Microlayers of pressure-sensitive material are designed to house and maintain a breathable personal atmosphere. The outer layer is hardened against attack.

Now, we look at relevant combat scores for each unit. The Terrans have an effective Accuracy of 4—they will need to roll 6+ to hit. The Vessamar have Toughness 2—they will need to roll 8+ to pass a Defense check.

First Pass

If there are 10 (9 + 1 leader) Terrans and 10 (9 + 1 leader) Vessamar with the above equipment and scores, the attack proceeds as follows:

1. Accuracy Step: The Terrans roll P10 +4, i.e. they roll 10d10 looking for 6+ results. They achieve 5 successes. That’s 5 individual figures who have managed to hit—they can contribute their attack effects, most importantly their Coverage.

2. Lethality Step: Each of our 5 hits contributes Coverage 4 from our G3 rifles—our total Coverage for this attack is 20. We roll P[Coverage] +Lethality, P20 +3, counting 8 successes.

3. Defense Step: Our 8 Lethality successes give us a total of 8 Damage. The Vessamar must allocate that Damage. With Protection 3, a Vessamar figure is saturated by 3 Damage. Two figures are saturated (3+3)—it would take 9 total Damage in order to saturate three figures. The saturated figures roll P1 +Toughness, P1 +2 in their case, and both fail. The Vessamar now have two Casualties—their unit size is considered 8 (7 + 1 leader).

Second Pass—Equipment Change

What if the Terran unit’s leader came into a weapons cache of far superior Light Infantry Rail Cannon rifles before the combat took place?

Name         |ACC Bonus   |COV  |LTH  |Range  |Special
LIRaC        |   +0       | 3   | 4   | 18"   | Brutal 0.5

This Argonaut Arms rifle has a large, rectangular barrel concealing two shock-hardened rails. Its diminutive tungsten payload reaches frightening muzzle velocities, propelled by a compact battery-and-coolant cartridge that can be refreshed in the heat of battle.

This weapon is substantially superior to the G3. The range and Lethality are improved, though Coverage is dropped. But the main factor is the Brutal keyword.

During Organization, a topic deserving its own later treatment, a unit is assigned a kind of equipment template which determines its unit-level behaviors and capabilities during combat.

When Organizing our 10 Terran fighters, the Force leader decides to assign the LIRaC as the template weapon (after assuring all requirements are met). Because the LIRaC contributes Brutal 0.5, our unit will end up with 10 × 0.5 = 5 points of Brutal.

To see the effect of Brutal, we look to the Attack Keywords rules.

Brutal X: At the beginning of the Defense Step, add X Damage.

Our attacking unit of Terran soldiers is equipped with a different weapon loadout. Let’s run through the attacking steps again to see how our attack will change and what the full ramifications are for this design.