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Old 08-31-2017, 08:27 PM   #1
Kfireblade
 
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Default Battletech/Mechwarrior mechs in GURPS

I'm going to be trying to run a campaign set in the battletech universe and I'm wondering if anyone has any good ideas for building the Mechs in GURPS?
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Old 08-31-2017, 08:37 PM   #2
Fred Brackin
 
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Default Re: Battletech/Mechwarrior mechs in GURPS

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Originally Posted by Kfireblade View Post
I'm going to be trying to run a campaign set in the battletech universe and I'm wondering if anyone has any good ideas for building the Mechs in GURPS?
After many, many considerations of the question I think the best ides to convert the mechs and still have them look like the original mechs is to build them as characters and use the Weapon Mount feature to hang the cannon class weapons from UT on them.

The advantages of this method would be the potentially great diversity of sizes, armor totals, movement rates and other stats. Other possibilities such as using Spaceships would have much less diversity and fidelity.

Possibly even simpler is to simply convert BT stats to Gurps stats while leaving any design system out of things.

The main conversion issue is that AP warheads (and particularly HEAT types) do not do in Battletech what they do in Gurps which is penetrate massive quantities of armor. When using the chargen system this can be represent by many layers of the Hardened Advantage (possibly as many as 4) with the Ablative or Semi-Ablative Limitations.
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Old 08-31-2017, 08:59 PM   #3
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Default Re: Battletech/Mechwarrior mechs in GURPS

I know a few folks are fond of running mech fights in their native system and the rest of the game in gurps.
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Old 08-31-2017, 09:11 PM   #4
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Default Re: Battletech/Mechwarrior mechs in GURPS

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Originally Posted by ericthered View Post
I know a few folks are fond of running mech fights in their native system and the rest of the game in gurps.
That leaves you with all the problems of the original system. Such as mechs v. non-megh units.
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Old 08-31-2017, 09:25 PM   #5
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Default Re: Battletech/Mechwarrior mechs in GURPS

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Originally Posted by ericthered View Post
I know a few folks are fond of running mech fights in their native system and the rest of the game in gurps.
That's what I did many years ago based on an article in Roleplayer #19. It was a fun game since the players were familiar with both systems.
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Old 08-31-2017, 09:25 PM   #6
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Default Re: Battletech/Mechwarrior mechs in GURPS

I would probably use the BT mech creation system and figure out a conversion from those stats to GURPS stats. Something like this:
  • Use the decade damage scale (1dHP = 10 HP)
  • Rule 1 point of BT internal structure is 5 dHP
  • Use BT armor values and say they are all semi-ablative DR
  • Use hit locations as normal in GURPS
  • Convert BT speeds in hexes/turn to yards/second
  • Generate GURPS stats for all the BT weapons; i.e. say an AC2 is: dmg 2d(3), acc 4, range 3000/10000, ROF 8, etc. Here you can either try to closely follow the BT stats, or make stats more in line with Ultratech.
  • You might want to say vehicular combat takes place on a larger scale with longer turns, like spaceship combat in GURPS Traveller, but figuring all that out could be a lot of work.
Now that will be some work, and afterwards you will have to look at the numbers to make sure there is some balance.
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Old 09-01-2017, 06:50 AM   #7
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Default Re: Battletech/Mechwarrior mechs in GURPS

I've run a Mecha game in GURPS 4e - using 5m tall Heavy Gear style mecha, not 12m tall Battletech style mecha, but I think the principles are pretty much the same.

My house rules from that campaign are below. You might want to adjust the scale: I was using MapTools to run the game online, so having 300 hexes on map was no big deal. Most of the rules are just clarifications on the existing rules for vehicle combat in GURPS Basic chapters 12, 13, and 17.

Terrain
'Mech scale combat occurs on maps using 5 yard hexes at rates of 1 second per action.

Trees are concealment, not cover, especially against large weapons. Every 5 yard hex of forest imposes a -2 penalty on attack rolls. This penalty is halved against SM+0 targets or the legs of SM+2 or more targets (since you're not firing through as much of the branches). Modifiers are cumulative.

Movement
'Mech scale combat occurs on maps using 5 yard hexes at rates of 1 second per action.

For simplicity, any large vehicle or giant that is moving on its legs is treated as a very large SM+0 character: they can accelerate to their maximum Move in a single action, or decelerate from their maximum Move to a dead stop just by not moving forward any more. They can also make tight turns, turning up to 180 degrees as part of a step or paying 5 MP per hexside change as part of a move action. They can move into any of their front 3 hexes, and turn to face the right and left front hexes as they enter them for free.

It costs 10 MP to enter a 5 yard hex of forest.

Control Rolls
A control roll is made against Driving (Mech) + Mech Handling - (Current Move MPs/10).

Failing a control roll in a turn causes a skid, so the 'Mech turns the way it intended but spends half of its current Move MPs moving in the old direction. Otherwise, failing a control causes the 'mech to randomly move 5 yards to the left or right or other movement as appropriate. Failing a control roll by more than the 'mech's stability rating also causes it to fall down down (and crash if it was moving at any speed, taking damage as though it collided with the earth).

Attacking
'Mechs have stabilized weapons and can Move and Aim. They still lose their Aim bonus if they make a defense roll, fail a control roll, or get hit by an attack that either does damage or knockback.

Attack and Piloting rolls during a Move and Attack maneuver are at -2 if the 'mech moves in anything other than a completely straight line or has to make any Control rolls. There is no penalty to attack or Control rolls made during an All Out Attack maneuver.
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Old 09-01-2017, 08:30 PM   #8
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Default Re: Battletech/Mechwarrior mechs in GURPS

I've used the basic BattleTech rules and GURPS skills. All I had to do was invert the BattleTech penalty sign (a minus two bonus in BattleTech becomes a plus two bonus in GURPS) and everything worked fine. Worked better then I expected, to be honest. It works, out of the box, needing no other modifications.

For 'Mech-scale damage, I just converted it to C-scale damage. That has a PPC doing 1,000 points of normal damage, which seems about right. Just state that 'Mech armor isn't ablative to non-C-Scale damage and you'll be fine.
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Old 09-02-2017, 05:57 AM   #9
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Default Re: Battletech/Mechwarrior mechs in GURPS

I probably wouldn't go more than decade scale for the mechs, but the last time I really played, it was stated that a regular infantry rifle could damage a mech. Something like a 1 in 6 chance that each shot would do 1 damage to a mech.

After all, a rifle infantry platoon is an actual threat to mechs, especially light mechs.
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Old 09-02-2017, 03:51 PM   #10
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Default Re: Battletech/Mechwarrior mechs in GURPS

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Originally Posted by sjard View Post
I probably wouldn't go more than decade scale for the mechs, but the last time I really played, it was stated that a regular infantry rifle could damage a mech. Something like a 1 in 6 chance that each shot would do 1 damage to a mech.

After all, a rifle infantry platoon is an actual threat to mechs, especially light mechs.
That was a very old rule that was dropped decades ago (MechWarrior 1st Edition, it was dropped in 2nd Edition and all later editions. Even in 1st Edition, it was a PC-only, lucky-shot rule). If you are firing personal weapons at a 'Mech, you're going to die. A full platoon of rifle infantry maxes out at 15 points of damage for 28 guys, bu-ut that's a cluster-attack, so it's not quite that clear-cut. You'd roll on the cluster table for 28, and an average roll would be 7-8, which means that 17 guys are going to hit the 'Mech, and that only inflicts 9 points of cluster damage, which, for infantry, is broken down into 2-point units.

While 9 points of damage is a threat to a light 'Mech, the weapons the 'Mech carries are probably a bigger threat to the infantry. Most lights pack some sort of anti-infantry deterrent, and, as we'll see below, those can be much more terrifying to the infantry then the infantry is to the 'Mech.

Using D-Scale means that the Puma, an 95-ton, main-battle tank, from the height of human technology in the Star League (circa 2750), would only have a frontal DR of 520. Which is less than half the DR of a T-72's frontal DR. And it's main weapon, a PPC, would only inflict 100 points of damage in a hit, meaning this vehicle would stand zero chance against a tank that is 800 years older than it.

In High Tech, the M4A1(76) has a DR of 210/105 and 158 HP.
In TRO 1945, the M4 has BAR 5 armor of 14 to the front with an IS of 3.

An successful hit from an AC/20 would obliterate the M4. In GURPS that works out to 1,158 points of damage. (That's 210 to get past DR + 948 to take it to -5xHP.) This isn't that the vehicle might be disabled, this is destroyed. This vehicle cannot be repaired, at best, you can scavenge some armor and bits from it.

Heck, a Medium Laser has a 50% chance of getting a critical hit on an undamaged M4 (due to the BAR 5 armor).

Taking 'Mech damage as D-Scale instead of C-Scale means that the AC/20 wouldn't, actually, damage the M4A1. A Medium Laser would only be slightly more powerful than a .50 cal, with an appallingly short range and no ability to auto-fire. An RPG would be more effective weapon than a 'Mech SRM launcher. And normal people would survive being hit by an LRM.

Also, a 'Mech-mounted machine gun does 2 points of anti-'Mech damage. That would equate to only a single hit of 20 points of personal-scale damage at D-Scale, and, really, that's only about 6d. That doesn't mesh with the description from Technical Manual:

Quote:
Originally Posted by BattleTech Technical Manual, pg 228
Heavier and capable of a far greater volume of fire than the weapons carried by conventional infantry or battle-suited troopers, these vehicular and íMech-mounted machine guns can flatten entire platoons of regular troops in just one or two passes.
While it is a bit of hyperbole, a normal machine gun takes out 2d6 infantry per shot in BattleTech (Cthulhu only gets d6 investigators per round . . .). So, with a couple of good rolls, it would only take three bursts for a machine gun to eliminate a rifle platoon. With average, it would only take four bursts. Not really possible for something that can only put out 20 points of personal-scale damage.

(Flamers take out 4d6 . . ..)

Now, the argument could be made that 20 points of damage is enough to eliminate a normal person in one hit (taking them to -HP, if they started with 10 HP). But, soldiers, especially in the Inner Sphere in the 28th through 32nd century, aren't normal people, and they all wear combat armor. This isn't Toad armor, or other powered armor, but, unless you're guerrilla fighters or from some backwaterless minor noble's personal army, you've got flak armor which will provide some protection against ballistic attacks.
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