Battletech to Gurps

[Juca]

Well, I did some... tests a while back, and I found them, but be warned: I did not actually played with these rules, I was only messing with GURPS since I found my old Battletech Boardgame (from the 90's!) and wanted to give Marauder, my favorite mech, a go.

I started simple, using the GURPS rules to find its hit points. It has 75 tons, and is unliving, which give us a ST of... about 220, though it would be more.
I treated it as an humanoid character, so it has 220 hit points, and each limb has HP/2, or 110 HP, to be more like the boardgame, where legs are sturdier than the arms, I gave it HP 100 to the arms, and 120 to the legs.
Also, using the same rules, we can give each extremity (be it a hand, or a weapon) HP/3, or about 75 hit points.
It is 12 meters tall, and almost humanoid (more like a giant chicken, but I digress), for a size modifier of +5.

For weapons, it has one particle cannon and one medium laser in each hand, and an auto-cannon/5 on its "back". Not wanting to reinvent the wheel, I've gone basic - the Particle Cannon is simply the TL 11 blaster cannon from UT

PPC - Damage 5dx20(5) burn sur, with RoF 1.

From it I tried to extrapolate the armor, the marauder should be able to take 2 hits from a PPC to its torso before going to internal damage (0 hit points?).
A hit from a PPC does an average 280 points of damage, so it needs about DR 900 to be able to take two hits from it and still be standing (at 0 hit points), I rounded it up to DR 1000 and divided it into DR 500 and DR 500 ablative, to be more like the boardgame.

The other weapons are also fairly easy to convert - the autocannon is a 25mm assault cannon with RoF 3 and using HEMP ammo, doing 6dx4 cr inc (10) with some explosive damage as extra.
The medium lasers are TL 11 Rainbow Laser Cannons, doing 6dx10(3) burn aaand thats it.

Yes, I know, it is not a conversion as per se, but maybe it can be used as a template, I don't know, I was just doing my hobby of converting things to GURPS.

Other thing that I was messing around was about the distances in the game. While the PPC in the tabletop reaches about a kilometer, the Blaster Cannon in GURPS has a 1/2 damage range of 120.000km... Maybe the warning, avoidance and protection systems on the mechs are so good that they have a very high chance of avoid/evade long range shots? I was thinking about giving the mechs +1 to dodge attacks beyond 250y, +2 beyond 500y, +3 beyond 1.000y... doubling for each +4.

Well, that's it. That was my attempt at building a Marauder in GURPS.

[David Johnston2]

Originally Posted by Prince Charon

Probably a good place to link to GURPS Spaceships 4: Fighters, Carriers, and Mecha. Admittedly, I haven't tried to make specific BT BattleMechs with that book, but I think it's possible. not sure about converting the heat sink rules, though. Kind of wondering if that's already been discussed elsewhere.

I find Spaceships insufficiently granular for something like this.

[Ulzgoroth]

Originally Posted by David Johnston2

I find Spaceships insufficiently granular for something like this.

I would definitely not even consider using Spaceships to model battlemechs. I don't see how it would even help at all.

For the most part Spaceships for mecha that aren't in fact spaceships is just a maybe okay design system, and Battletech already has a design system.

[Mark Skarr]

I wouldn't consider translating 'Mechs directly into GURPS. I've tried. Going that way leads to madness. You wouldn't get anything approaching what they are in BattleTech. 'Mechs are--orders of magnitude--tougher than anything seen in GURPS at their size. After all, 'Mechs can take hits, past their armor, from main battle tanks, and not be obliterated.

If you want to keep the BattleTech feel--just keep BattleTech. Use GURPS for the character-scale stuff, and switch to BattleTech, still using GURPS skills for 'Mech battles.

I, personally, take a chainsaw to the skill list. And, it's Pilot (BattleMech) not Drive (BattleMech). Additionally, just have Gunner (BattleMech). Not the individual weapon types because you're not shooting them directly, you're using the 'Mech's targeting system. It makes more sense than Gunner (ACs) and Gunner (Lasers) for a Rifleman pilot. And FSM forbid you pilot a Shadow Hawk (because, you want to be seen from orbit when your ammo gets hit).

If you want, have a technique that allows you to be a better shot with specific weapons (say an Average technique that starts at +/- 0 and can go to a max of +4).

[Fred Brackin]

Originally Posted by Juca

For weapons, it has one particle cannon and one medium laser in each hand, and an auto-cannon/5 on its "back". Not wanting to reinvent the wheel, I've gone basic - the Particle Cannon is simply the TL 11 blaster cannon from UT

PPC - Damage 5dx20(5) burn sur, with RoF 1.

.

The OP has said he didn't want to focus on 'Mech combat but it can be quite useful to at least know how much character-scale damage a 'Mech weapon does.

UT is actually pretty useful for this. You've actually got a TL10 Blaster Cannon and you use this for the Inner Sphere model and save the TL11 version for the Clans.

You're also good for 3 sizes of Lasers at TL10 w/improved models at tL11.

The Tripod flamer might be a little small but that's not a common 'Mech scale combat weapon.

The TL9 100mm Tank gun will do for the AC/5. The earliest BT fluff and technobabble I ever encountered wanted it to be 120mm. Anyway you want to keept he big size for area damage to squishies not in 'Mechs or armor.

Use 64mm warheads for LRMs and 100mms for SRM.

There's a Pyramid pdf with more TL9 cannons and missiles. It's 3/37 and might fill out your AC selection.

The most important thing about 'Mech armor is that's it's Hardened (probably 4x). The HEAT warhead trails only the Atomic Bomb as the most important military invention of the 20th century and 'Mechs seem to be largely immune to them or at least their (!0) armor divisors.

You might want Pyramid 3/37 for character scale weapons because it lets you design a large variety of Laser weapons instead of having all Laser Pistols doing 3D(2).

For other character scale weapons you're largely set with UT except for "Needlers". Needlers are common in BT fiction and were decent choices in the vrious MechWarrior games I've had (and even in Gurps3e). Gurps 4e Needlers are poor choices for most purposes but changing their damage type fom P- to Impale would at least help a little.

[Ulzgoroth]

Originally Posted by Fred Brackin

The TL9 100mm Tank gun will do for the AC/5. The earliest BT fluff and technobabble I ever encountered wanted it to be 120mm. Anyway you want to keept he big size for area damage to squishies not in 'Mechs or armor.

What? ACs are autocannons. And they're almost entirely useless against squishies unless loaded with flechette ammunition (which for whatever reason isn't part of the tech base until quite late). This is how you make something that doesn't even slightly resemble Battletech.

Battletech fluff has autocannon classes not be tightly linked to caliber - two different documented AC/5s are 80mm and 120mm.

Originally Posted by Fred Brackin

The most important thing about 'Mech armor is that's it's Hardened (probably 4x). The HEAT warhead trails only the Atomic Bomb as the most important military invention of the 20th century and 'Mechs seem to be largely immune to them or at least their (!0) armor divisors.

The most important thing about battlemech armor is that it is ablative! That shapes everything about how battlemechs are armed and used. There are almost no mech weapons that expect to penetrate their target's armor on the first hit.

It's also not immune to AP effects, since AP autocannon shells and tandem-charge missiles can cause behind-armor effects against any thickness of standard armor. It may be effectively protected against HEAT penetration though.

[Fred Brackin]

Originally Posted by Ulzgoroth

What? ACs are autocannons. And they're almost entirely useless against squishies unless loaded with flechette ammunition (which for whatever reason isn't part of the tech base until quite late). This is how you make something that doesn't even slightly resemble Battletech.
.

BT "autocannons" are "auto" in the sense they have no human loaders. They are not necessarily similar to anything the 20th or 21st centuries labeled as such.

BT "autocannons" _are_ useful against infantry formations.

Just making 'Mech armor ablative doesn't keep it from being one-shotted by a shoulder-launched HEAT missiles. Hardening does. To make such SRM-equivaltns useful against "Mechs in BT you have to launch them in volleys from whole platoons.

[Mark Skarr]

Well, a normal AC/5 is just DB, S. So, it's Direct-Fire Ballistic and Switchable ammo. It is not AI, or Anti-Infantry, so, it follows the normal rules for shooting at infantry. So, a Direct Fire weapon hits Damage Value / 10 (so, for an AC/5 it's 0.5) troops. And you round these fractions up, and one trooper is hit and eliminated.

An LB 5-X AC, is DB, C/S/F††, so it can count as a cluster weapon, if loaded with cluster munitions. So, it's Damage Value / 10 +1, so 1.5 or 2 troopers hit and eliminated. A 100% improvement vs standard ammo.

Your 8-ton weapon is not useful against infantry formations. Don't waste the ammo.

If you're fighting infantry, get thee a flamer or machine gun. A standard machine gun is, at a minimum, as effective as an LB 5-X, as it rolls 2d6 for damage against infantry. And a flamer makes it warcrimes o'clock with a whopping 4d6 vs infantry.

(This information is in Total Warfare, pg 216-217.)

If you want to keep the BattleTech feel, don't convert BattleTech into GURPS existing items. You'll have to make your own. I did that for Heavy Gear. But, to be fair, Heavy Gear works better in GURPS than it does in it's own system.

[Ulzgoroth]

Originally Posted by Fred Brackin

BT "autocannons" are "auto" in the sense they have no human loaders. They are not necessarily similar to anything the 20th or 21st centuries labeled as such.

They are specifically characterized as firing in bursts.

Originally Posted by Fred Brackin

BT "autocannons" _are_ useful against infantry formations.

What rules are you reading? The ones I'm reading say that they're pretty far up the list of worst possible weapons against infantry - again, unless equipped with that one specialized ammo type. They're as useful against infantry as a tank gun firing sabot.

Originally Posted by Fred Brackin

Just making 'Mech armor ablative doesn't keep it from being one-shotted by a shoulder-launched HEAT missiles. Hardening does. To make such SRM-equivaltns useful against "Mechs in BT you have to launch them in volleys from whole platoons.

Lots of things could stop them from being one-shotted by HEAT, but the armor being ablative is one of the most obtrusive setting features. Both are important, but I can't fathom describing the latter as less important.

[Fred Brackin]

Originally Posted by Mark Skarr

Well, a normal AC/5 is just DB, S. So, it's Direct-Fire Ballistic and Switchable ammo.

Those stats appear a rather late edition of the rules that I don't own.

I could draw from Citytech 1st ed where an AC/5 did 5 pts of damage to an infantry platoon basically killing 5 soldiers.

There's also my 1st printing of the 3025 book that makes thet "thing" on the back of the Marauder a 120mm autocannon. The Grey Death Legion novel agrees. It dies have it firing a 4 round burst but it doesn't specify a time period for how long that takes.

That's 'BattleTech" to me.