If you've watched our battle reports, you might have noticed we play with a series of optional rules published in the Battlemech Manual, Total Warfare, and some out-of-print supplements like Strategic Operations. This post itemizes all of the optional rules we use, and provides details (and some light analysis) on the house rules we've implemented at DFA Wargaming. When it comes to choosing optional and house rules, our top priorities are balance and speed of gameplay - but we also keep an eye towards recreating a feeling that is true to both Classic BattleTech and the MechWarrior game series we all love.
Default Skill Ratings
Clarification: Our standard MechWarrior has a gunnery skill of 2 and a piloting skill of 4. This allows for more hitting and less tripping over your own feet.
Default Forest Height
Clarification: Our "default" forest is level 3. In BattleTech, each level is roughly 5 meters (about 16.5 feet). The rules recommend treating forests as level 2 terrain (33 foot tall trees seems reasonable), but google says the average tree height is anywhere between 40-70 feet. We decided that level 3 (roughly 50 feet) was a good compromise, requiring at least a level 2 hill or building for a mech to be able to see over the forest.
Backwards Level Change
Reference: BattleTech Battlemech Manual pg. 15
Reference: BattleTech Battlemech Manual pg. 19
Expanded Arm Flipping
Reference: BattleTech Battlemech Manual pg. 25
Reference: BattleTech Battlemech Manual pg. 45
Reference: BattleTech Battlemech Manual pg. 49
Expanded Damage Modifiers
Reference: BattleTech Battlemech Manual pg. 55
Reference: BattleTech Battlemech Manual pg. 99
Machine Gun Rapid Fire Mode
Reference: BattleTech Battlemech Manual pg. 101
Modified Optional Rules
Expanded Reckless Movement
Reference: BattleTech Battlemech Manual pg. 20
Reference: BattleTech Battlemech Manual pg. 81
Reference: Tactical Operations pg. 85
Reference: Strategic Operations pg. 393
Always Round Up
Ruling: When playing without a hex grid, ranges can get confusing - especially when some of the RAW in Strategic Operations tell us to round up (like when measuring range), but to also round down (calculating minimum range). What about shooting through a half-inch of forest? Or moving through 1.5" of rubble? Or physical attacks? At DFA, we simple use the "round up" rule when it comes to measuring distance.
Mechs Provide Cover
Ruling: Mechs can block and limit LOS just like other "hard cover" such as buildings. In RAW, mechs do not provide cover.
Ruling: Mechs equipped with usable jump jets can "boost" while running to clear difficult terrain or obstacles that are no wider that 1 hex or 1", and no higher than level 1. Boosting cannot be used in consecutive hexes or inches (i.e. they need to touch down after clearing an obstacle). A mech may boost a total number of times equal to their available jump MP, but total combined movement may not exceed their available walk MP x 1.5 (current run MP). Mechs generate 2 heat for running, plus 1 additional heat point for each jump MP spent in this way. The mech is assigned a +3 attacker modifier (as if jumping), but their target modifier is based on distance moved only (no additional bonus assessed, unlike normal jumping). Mechs cannot change facing while boosting in a hex and must expend run MP as normal.
The red circles indicate where the Catapult boosted to enter the hex. In total, the CPLT-C1 would spend 6 MP, move 5 hexes (plus a facing change), build up 4 heat, and have a +3 attacker mod and a +2 target mod. Even though the Catapult has Jump MP remaining, it cannot move any further as it spent 6 MP, which is the maximum MP for that mech when running.
Revised Range Penalties
Ruling: We have revised the range penalties as follows: Short +0 / Medium +1 / Long +2 / Extreme +3
Ruling: Instead of using the cluster hit table to determine the number of munitions that strike a target, use the following rules: determine the number of clusters the weapon produces (e.g. an LRM-5 has one, while an LRM-20 has four - this is because LRMs are grouped into clusters of 5 missiles each as described in the rules). For each cluster, roll a single die. A roll of 3+ will result in a cluster hit, a roll of 1 or 2 means the cluster misses. If all of the clusters for a single attack miss, the weapon always does a minimum of 2 damage. If a missile launcher is equipped with Artemis, the same rules apply, except the player may reroll any 1s (once). A resulting 3+ will hit. If all of the clusters miss on an Artemis-equipped launcher, the same minimum 2 damage applies. These rules apply to other cluster weapons as well, like the LBX-10.
Ruling: When rolling to hit, players roll a d6 that represents their "pilot" die, and another d6 for each weapon being fired. The pilot die is then added to each of the individual weapon die to determine a hit or a miss. Various size and color dice are used to represent different types of weapons (we have a chart for that later). When rolling for location, players follow the same pattern rolling a d6 to represent their "pilot" die, and another d6 for each weapon that hit the target. The pilot die is added to each individual weapon die to determine location.
Clarification: Pilots can opt to fire in chain mode (following RAW word-for-word), rolling 2d6 separately for each weapon - when chain firing, all location rolls must also be separate 2d6 rolls. Additionally, any time the pilot chooses to group fire at more than one target (per the secondary target rules), they must make a separate gunnery roll for each attack. Said differently, they would roll a pilot die + weapon dice for the first target, then roll a pilot die + weapon dice for the second target. We are also aware of the group fire rules that exist in Strategic Operations, and do not use them at all.
Aside from hitting mechanics, group-fired weapons have have a negligible increase in probability to hit the same location multiple times. Overall the probability to hit a given location in chain or group fire does not change more than 1.3%, showing that group fire is in largely inline with RAW probabilities. In terms of floating criticals and headshots, the probability of rolling multiple 1s or 6s in a group of three weapons is less than one tenth of one percent (>0.1%).
Dice Reference Guide
Clarification: Since group fire allows players to roll all their weapons at once (i.e. a fist-full of dice), it's important to distinguish one weapon from another. At DFA, we use different size and color dice to accomplish this. The sizes we use are 19mm, 16mm, 12mm, 8mm. Red dice represent lasers, white dice stand in for ballistics, black dice account for missiles, and blue dice constitute PPCs. The larger the die, the more powerful the weapon - for example, an AC/2 would be an 8mm white dice, and an AC/20 would be the massive 19mm white dice. You can choose to use any colors or sizes that make sense to you, and more importantly, that you have available. With the introduction of 3050+ tech, you can use translucent dice or additional colors to represent tech like extended range or pulse weapons, or special modifiers like damaged arm actuators. The infographic below illustrates how we typically assign dice to weapons: