In general, its cheaper to use vehicles than mechs pretty much regardless of what you're doing. Whether they're civilian models or military models. There are logistic concerns such as space, fuel, etc., but civilians aren't exactly doing planetary landings, as such field trucks and/or driving the vehicles themselves is more than sufficient. One needs to worry about the supply vehicles, of course, as they need to be protected and replenish the other vehicles, especially if any of them are sporting ICE + Power amplifiers in order to power lasers, as that consumes fuel faster. Chemical lasers don't have this issue.
I don't really use custom rules much, aside from when it pertains to a more hardcore breakdown of weapon variants. And that's more changing how damage is distributed / checking for hits. (As an example, an SHK's 80mm AC/5 might do quite a few shots but each is only a fraction of the five damage, while a Marauder's GM Whirlwind/5 is 3 shots to get 5 damage, as such if broken down, the SHK's more likely to get hits more often and more hits per firing, but the damage isn't all that substantial compared to just one shell hitting of the Whirlwind/5).
Megamek's inclusion of pretty much all the existing rules is more than plenty, and I occasionally have civilian presence in my campaigns.
I've actually recently made three basic vehicles based heavily on a real life vehicle that's at my work.
Well three variations of the same vehicle. Its got the simple name of Improvised Artillery with the variant being what it has equipped (mortar, rifle, primitive AC/2).
12 ton 4 wheeled vehicle. 3/5 movement using standard ICE. Dune Buggy movement enabled (to account for the real life vehicle's large super-thick-tread tires, dynamic suspension and four-wheel turning). The engine is 1 ton.
Crew of 1.
Using 1.5 tons of commercial armor or industrial armor depending on your preference (more protection per ton for commercial, but weapons will be significantly more likely to get critical hits through armor. Only get a few points of armor for industrial but only as likely to receive a through-armor hit as military grade armor). Either way it works out and gets the desired effect; these are civilian vehicles modified to carry a hefty weapon, not military vehicles).
Armor distribution: Even.
(Considered having it lower on the left side to reflect the real life vehicle's open air cockpit.)
No turret. Weapon mounted forward only.
Rear trailer hitch, to allow it to haul a trailer with additional ammo or fuel as necessary.
Weapon:
Mech Mortar 2 with 2 tons of ammunition (7 tons total). (Considered twin Mech Mortar 1s and 3 tons of ammo to reflect a faster, more chaotic firing rate. But want it to be clear its only got one barrel). Included is a targeting system / FCS.
OR
Mech Rifle (Medium) and 2 tons of ammunition. (7 tons total) For a canon with Umph, even if slow firing cannons are obsolete, this is still very effective (6 damage per hit) against other civilian targets. Against a military target, though, this is gonna show it is clearly outmatched when they net an average of 3 damage per hit.
OR
Primitive AC/2 with 1 ton of ammunition. (7 tons total). Nice, fast rate of fire. Can spew out around 4 damage per turn at the risk of jamming it/consuming the ammo too fast. Paced a bit better, it'll do fine in numbers, but on paper the Mech Rifle outclasses this design even against military targets, only able to potentially outperform if the AC is pushed to its limit and the point of a potentially deadly misfire or jam. The Rifle is also more accurate, due to this being a primitive AC/2 rather than a military model.
Note: All 3 variants of this Improvised Artillery Vehicle are less than 120,000 cbills. The cheapest version (with the Mech Mortar) is less than 68k.
Its hard not to imagine it having a cannon, considering the fully extended 'fork' looks like a long, square cannon.
The original vehicle is closer to 11.5 Metric tons than 12, but I rounded up to make the weapons possible.
Another similar but older vehicle we have is called the Sky Trek on the side, but for some reason everyone has nicknamed it the "Sky Dragon".
As such, Sky Dragon may be a name I use.
Edit: Fixed an error above.
Also, made one more variation using an LRM-10. Thought of using rocket launchers or LRM (OS), but the issue comes up that there'd be a lot of left over tonnage and too many missiles. Given the option I went for primitive, not to reflect that it's an ancient launcher, but to better represent its abilities as a primitive launcher has a number of negative effects reducing its effectiveness against certain kinds of targets. Not certain if I'll go the 2 ton ammo route, or if I'd go the Communication equipment route (in order to allow it communication for indirect fire).
I also have numerous police model mech designs. Specifically 3 unique chassis, and variations made by different locations and purposes. One of which is named, the Nin Kei though it isn't finalized as to whether it is 20 or 25 tons. Two are based loosely on Patlabor designs at 20 (or 25 tons, not finalized yet) and 10 (or 15 tons also not yet finalized).
The heavier of the two are based on this, and as such the cockpit is placed into the center torso.
The "Ejection" seat, however, is a slot placed in the head. The desired result works very well, if the head is damaged, the ejection seat can be rendered non-functional, preventing any possibility of ejecting in case of emergency. This also allows for a basic weapon to be put into it, which can act as a turret with 90 degree rotation (45 left, 45 right). Its hand-held weapons are considered "Jettison-Capable" and as such can be abandoned and picked up in the field, and switched out within an hour in the mechbay. In the field the switching is actually closer to 2 turns (because dropping consumes 1 turn, picking up consumes 1 turn). Though the weapon needs to be in the field, and unless it shares the same ammo, no reloads can be picked up with it.
It works pretty well, especially when using pilots with unique skills. Two pilots I have based on the Patlabor series, Oda and Naomi, play very differently.
Oda is a clumsy pilot, but excels at accuracy, able to functionally fire and accurately hit things even when the fire control software is non-functional, as well as pull off some impressive shots. He tends to cause more damage to his own machine than to the enemies, due to being brash, impatient and impulsive. Even when given to an AI with a personality to match, he'll take unnecessary risks to land in the good shots, including one time where he "skid" (so lets assume if it was intentional, a power slide) an extra 90 meters in addition to his run and trip, and followed up with a well place shot while laying down that netted a headshot on his clone (yay for testing design functionality by having AI fight AI in Megamek).
Noami is a terrible shot, if the FCS is down she's more likely to shoot herself in the foot. However, she has Melee Specialist and Melee Master, and as such can perform multiple melee attacks in a single turn, with limits such as 2 kicks, 3 punches, 2 punches and a kick (with a risk of falling over), and tackle-and-punch. Combine with sprinting, and needless to say.... it's incredibly fun...and all perfectly legal in tabletop rules.
For comparison the "Copper" police mech is 25 tons, the "Guardian" police mech is 15 tons (with its 5 machine guns), the Guard quad-leg Security Mech is 15 tons, the Inquisitor is 35 tons, and the Pacifier is 30 tons. All of these are classified as Industrial Mechs with the exception of the Guardian, which is classified as a Battlemech for civilian police high profile enforcement.
Of my designs, the Nin Kei is a Battlemech with commercial armor, the rest are Industrial Mechs.
For the most part, they're less than 200,000 cbills with only a couple of exceptions.
I'm working on more vehicles occasionally, and will have a collection to share at some point. As for more civilian oriented campaigns, I can't promise they will be expressly civilian oriented, but I have had plans for fun involving civilian and improvised weapons.
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As for rules, when playing less with vehicles and more with people, Battletech scales up and down... Down at the infantry level, CityTech is a good place to start, as it gives infantry, smaller areas such as inside buildings, corner shooting, cover mechanics, etc. This would be where you might want your civilian combat to be, as it puts an emphasis on the people and the individual actions as opposed to what I have to do on the Vehicular level, in which people are literally 1 hex groups of 5 or more people.
Edited by Koniving, 19 January 2019 - 11:59 PM.