In my last post I showed how most Battlemechs couldn’t actually walk as fast as described in the game – if you missed that then you can read it at How fast can a Battlemech walk?. In this post I will present some optional Advanced Rules to implement the more realistic mech movement described there.
This is what I’m setting out to achieve here:
– Mechs now walk, run, and sprint at realistic speeds.
– Where possible, movement rates should be as consistent as possible with their current stats. That said, the fastest mechs must be slower here because it’s now impossible for them to be as fast as they were – this means they will have smaller engines and more space for equipment.
– It must be possible to design mechs so that their engine ratings (and gyros) are comparable with published designs.
– MASC, Superchargers and TSM will have a similar effect on speed as in the existing rules.
Advanced Rules: Realistic Mech Movement
There are now five basic Mech movement modes: Standing Still, Walking, Running, Sprinting (this is different to Sprinting as described in the BT rules), and “Overdrive” (this can be considered to be a ‘super sprint’). Not all of these movement modes will be available to all mechs – this depends on the leg length of the mech and the desired maximum speed of the mech when designed. Some mechs may only Walk, some may only Walk and Run, some may also Sprint and possibly Overdrive. Leg Length is related to the height of the mech, which is related to their weight class – heavier mechs are usually taller than lighter mechs and therefore have longer legs. It is possible for mechs to be designed with longer legs than are normal for their weight class, which allows them to reach faster speeds – this can be accomplished by taking the new Long Legs quirk.
The Realistic Movement Table below shows the basic movement types for each weight class of mech (Light = 20-35t, Medium = 40t-55t, Heavy = 60-75t, Assault = 80-100t):
This table shows the maximum possible speed (given in MP per turn) that each movement mode can reach for a given weight class/leg length. If any mech spends 0 MP in a turn then it is Standing Still. A Light mech with its default leg length of 4-5m is Walking if it moves 1 or 2 MP during a turn (grey boxes), Running if it moves 3 or 4 MP in a turn (green boxes), Sprinting if it moves 5 MP in a turn (yellow boxes), and in Overdrive if moving 6, 7 or 8 MP in a turn (red boxes), and cannot normally move faster than 8 MP in a turn. Note that the table does not define the actual speed limits of a mech – those are determined by its engine rating (see below). The Light mech described in this example would be listed as having a movement of “2/4/5/8”.
Standing Still, Walking, and Running work as described in the Battletech rules.
Sprinting (revised): Sprinting here is the same as Running but generates 50% more heat than Running (3 heat for normal engines, 9 heat for XXL engines). Firing weapons is possible while Sprinting but the Attacker gets a +3 Target Number modifier. Sprinting is only possible if all of the Mech’s legs are present and no critical hits have been inflicted to any Hips, Leg or Foot actuators.
Overdrive: Overdrive works the same way as Sprinting as described in the Battletech rules. Overdrive is only possible if all of the Mech’s legs are present and no critical hits have been inflicted to any Hips, Leg or Foot actuators.
MASC and Superchargers: MASC and Superchargers allow the mech to move up to 2.5 times (rounded up) its Run MP, even beyond the normal maximum allowed for its leg length. Thus, a Mech with Run 3 can move up to 8 MP with MASC, a Mech with Run 4 can move up to 10 MP with MASC, and a Mech with Run 5 can move up to 13 MP with MASC. This is considered as Sprinting up to the Sprint limit, and Overdrive if beyond that limit. This movement is allowed even if the Mech could not Sprint or Overdrive before MASC was activated (the mech must at least have a Run speed to use MASC or Superchargers, however). Standard rules for operating MASC and Superchargers still apply. If a Supercharger and MASC are combined then the mech may move up to 3 times its Run MP (i.e. up to 9 MP for 3 Run, 12 MP for 4 Run, 15 MP for 5 Run) – again, this applies even if the MP is beyond the Mech’s normal Overdrive limit.
Triple Strength Myomer (TSM): Triple Strength Myomer adds +1 to the Mech’s Running, Sprinting, and Overdrive MP (it does not affect Walking MP). A Light mech with a default of 2/4/5/8 movement would have 2/5/6/9 movement with TSM. TSM cannot be used with MASC. If TSM is combined with a Supercharger then +1 to the Run MP first, then multiply that value by 2.5.
MASC Example: An Executioner (Assault mech with standard legs) has 3/5/6/- movement without MASC, but with MASC it has 3/5/7/13 movement (5 x 2.5 = 12.5, rounded up to 13) – with MASC active it can sprint at 7 MP and Overdrive at 8-13 MP. If it had a Supercharger active at the same time it would be able to move 3/5/7/15 (5 x 3 = 15).
Supercharger Example: An Urbanmech (Light mech with standard legs) has 2/3/-/- movement without a Supercharger, but with a Supercharger it has 2/4/5/8 movement (3 x 2.5 = 7.5, rounded up to 8) – with the Supercharger active it can run up to 4 MP, Sprint at 5 MP and Overdrive at 6-8 MP. If it had MASC active at the same time it would be able to move 2/4/5/9 (3 x 3 = 9).
Supercharger + TSM Example: If our Urbanmech had a Supercharger and TSM, then with just the Supercharger active it would have 2/4/5/8 movement. With just the TSM active it would have 2/4/-/- movement. With both active it would be able to move at 2/4/5/10 (4 x 2.5 = 10).
Jump Jet limits: Mech jump MPs are now limited to the mech’s listed Sprint Speed. If the mech cannot Sprint then the limit is their listed Run speed instead. e.g. a Spider’s Sprint limit is 7, so it now has Jump 7 (and 0.5t of free space since it no longer needs one jump jet) instead of Jump 8. An Urbanmech cannot Sprint but its Run limit is 3, so it can have up to 3 Jump MP (it actually has 2 Jump MP).
Mech Design Changes
Generally speaking, lighter mechs are smaller and therefore have shorter legs, which means they transition to different movement modes at lower speeds than larger mechs with longer legs. However, engines are much heavier for larger mechs at a given speed, so while Heavy and Assault mechs have the potential to move faster they are unlikely to ever reach those higher speeds because they would not be fitted with large enough engines.
The Leg length for mechs that do not have the Long Legs quirk is assumed to be half of the height of the mech, as shown for each weight class in the RMT. However, mechs may take up to three levels of a new Long Legs Quirk when designed – each level lengthens their legs so that they are equivalent to the next (heavier) weight class, which allows them to move faster. For example, a Locust has 7m tall legs because it has the Long Legs 3 quirk, which allows it to reach speeds up to 11 MP (its legs are as long as those of an Assault mech, so it can move at 3/5/7/10 and Walk at up to 3 MP, Run at 4-5 MP, Sprint at 6-7 MP and Overdrive up to 10 MP). Without long legs, a Light mech would not be able to move faster than 8 MP.
The disadvantage of Long Legs is that they are more fragile than normal legs – a Mech with Long Legs must take the Weak Legs quirk at the same level, which balances out the positive aspects of the quirk (Weak Legs is modified here to cost 1 to 3 points).
A Mech with this Design Quirk has longer legs than the norm for its weight class, which increases the speed at which it can Walk, Run, Sprint, or Overdrive. The mech is considered to be a heavier weight class on the Realistic Movement Table for each level of Long Legs taken. For example, a Firestarter has Long Legs 1, so it uses the Medium row of the RMT instead of the Light row (one row down from the “Light” row). A Locust has Long Legs 3, so it uses the Assault Mech row of the RMT instead of the Light row (three rows down from the “Light” row). A Cicada has Long Legs 3, so it uses the 9m row of the RMT (their legs are even longer than those of Assault mechs). Mechs may not take more than 3 levels of Long Legs, and may not have legs longer than 9m. Long Legs are usually found on Light and Medium mechs.
Weak Legs 1: This mech’s legs were never designed to take the stresses involved in physical attacks. If the Mech executes a Death From Above attack, roll on the Determining Critical Hits table for each of its legs. If it is kicked in a leg, roll on the table for the leg that was kicked. In both cases, the critical check occurs even if the leg armor was not breached. (This is the official errata’d version of the Weak Legs quirk in BM p89.)
Weak Legs 2: As Weak Legs 1, but the PSR made after being kicked or landing from a DFA is made with an additional +2 target number modifier (the attacker’s PSR roll after a DFA now has a total modifier of +6!).
Weak Legs 3: As Weak Legs 2, but the Determining Critical Hits roll has a +1 modifier (a modified result of 13 is the same as a result of 12).
Calculating Engine Ratings
Engine ratings are no longer calculated based on Walking speed. Instead, first decide the Desired Maximum Speed (DMS) in MP for the mech (up to a maximum of 11) – if this is above the maximum for the mech’s weight class shown on the Realistic Movement Table then you must add at least enough levels of the Long Legs quirk (and associated Weak Legs quirks) to allow it to reach the required speed. For example, if you want to design a Medium Mech with a DMS of 10 (available to Assault mechs with 7-8m long legs) then you will need to give it Long Legs 2 (and Weak Legs 2) to allow it to move that fast. If the DMS falls within the Mech’s Sprint range, it cannot Overdrive. If the DMS falls within the Mech’s Run range, it cannot Sprint or Overdrive. If the DMS falls within the Mech’s Walk range, it cannot Run, Sprint or Overdrive.
The Engine Rating is calculated by multiplying the Engine Factor associated with the DMS by the Tonnage of the mech – if the result is not a multiple of 5 then round up the engine rating to the next multiple of 5 (e.g. a calculated rating of 201 to 204 rounds up to 205):
In the Rules As Written (RAW), the Walking Speed of the mech is multiplied by the Mech Tonnage to get the Engine Rating, and then the Walking Speed is multiplied by 1.5 to get the Running Speed. Here, we’re working in the opposite direction from that – we’re starting with the Desired Max Speed, multiplying that by 2/3 (dividing by 1.5) to get the Engine Factor, and then multiplying that by the Mech Tonnage. This gives us Engine Ratings (and gyros) that are largely the same as the canonical values, except for the fastest mechs (since speeds of 12+ are no longer available). A side effect of this is that we can now have mechs moving at a max speed of 1, 4, 7 or 10 MP, which was not possible before because no integer can be multiplied by 1.5 to get those numbers – these are now possible by giving them non-integer engine factors (0.5, 2.5, 4.5, 7.5 respectively).
Design Example 1: We want a 65t Crusader to have a DMS of 6 – this is a Heavy mech with unmodified legs. This falls within the Sprint range (6-7 MP) for a Heavy mech, so the Crusader would be listed as having a movement of “3/5/6/-“. This means it would be Walking up to 3 MP, Running at 4 or 5 MP, and Sprinting at 6 MP. It would not be able to move faster than 6 MP, so Overdrive is unavailable. The Crusader DMS of 6 means it has an Engine Factor of 4, multiplied by its tonnage of 65t means it has an Engine Rating of 260 (identical to its rating in the RAW).
Design Example 2: We want a 40t Cicada mech to have a DMS of 11 – this is a Medium mech with Long Legs 3. This falls within the Overdrive range for a mech with 9m legs (9-11 MP), so the Cicada would be listed as having a movement of “3/5/8/11”. This means it would be Walking up to 3 MP, Running at 4 or 5 MP, and Sprinting at 6, 7, or 8 MP, and in Overdrive at 9, 10, or 11 MP. The Cicada’s DMS of 11 means it has an engine factor of 7, multiplied by its tonnage of 40t means it has an Engine Rating of 280. Since the Cicada can no longer move at 12 MP, its engine is lighter than it is in the RAW (16t for a 280 vs 22.5t for a 320) and its Gyro is a ton lighter as well since that is based on the Engine Rating. This gives it an extra 7.5t of space to fill with weapons, armor or heatsinks (it could certainly do with more armor!).
Design Example 3: We want a 45t Medium Mech with unmodified legs to have a DMS of 7. This falls within the Overdrive range (7-9 MP) for a Medium mech, so it would be listed as having a movement of “2/4/6/7”. This means it would be Walking up to 2 MP, Running at 3 or 4 MP, Sprinting at 5 or 6 MP, and in Overdrive at 7 MP. It would not be able to move faster than 7 MP. The mech’s DMS of 7 means it has an Engine Factor of 4.5, multiplied by its tonnage of 45t means it has an Engine Rating of 202.5, which is rounded up (to the nearest multiple of 5) to get a final Engine Rating of 205.
Design Example 4: We want a 30t Urbanmech to have a DMS of 3 – this is a Light mech with unmodified legs. This falls within the Run range (3-4 MP) for a Light mech, so the Urbanmech would be listed as having a movement of “2/3/-/-“. This means it would be Walking up to 2 MP, and Running at 3 MP – it would not be able to Sprint or use Overdrive and cannot move faster than 3 MP. The Urbanmech DMS of 3 means it has an Engine Factor of 2, multiplied by its tonnage of 30t means it has an Engine Rating of 60 (identical to its rating in the RAW).
Revised Movement Charts for Common Battlemechs
Recalculated stats for 3025 mechs and some Clan mechs are shown in the table below. J# is how many Jump MP the mech has. LL1-3 is how many levels of the Long Legs Quirk the mech has. ER:# is the new engine rating of the mech (if it has changed). +#.#t is how much free tonnage the mech now has because of its smaller engine (and possibly smaller gyro too).
I have further thoughts on refining the movement system, but I’ll leave that for (yet) another post!
As always, thanks for reading – if you have any (constructive) comments, questions, or observations then please let me know in the comments!