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Old 06-19-2023, 01:43 AM   #1
seasalt
 
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Default GURPS Spaceships: Lethality reduction rules switches

The purpose behind these is twofold. Firstly - in an attempt to be realistic, I contend that the baseline rules jack up lethality to the point where it is frankly UNrealistic and assumes ships have no damage control, no reactive armor or damage-absorbing features, and fails to account for overpenetration.

Secondly - to make spaceship combat a bit more fun and interesting, allow ships to at least SURVIVE hits by a serious weapon even if they take crippling damage, to make damage control and destruction of individual components more meaningful (since in the baseline rules, spaceships are either at full health, or instantly dead if hit by anything). Tactically it lets you build spaceships that are actually hard to kill if they specialize in armor and point defenses.


1. All armor is semi-ablative (giving it 400% dDR) as per the rules in the gurps spaceships "optional rules" fan expansion pdf.

2. All guns and launcher projectiles lose their default AP divisor. Instead of losing their AP, proximity bursting projectiles do 1/10th damage. [Note: this is a stronger version of the "advanced armor" rule from Spaceships 3]

3. Whenever a non-volatile component is destroyed by non-explosive damage (i.e. not a nuke blast and not a direct hit from a conventional gun shell or a missile), the remaining damage beyond any required to cripple that component is lost due to overpenetration.

4. Due to overheating, tube length, and other issues (or whatever technobabble you prefer), shift the damage value of all lasers except for tertiary armaments twos column to the left.

5. Apply the "Advanced damage control" switch from Spaceships 3, effectively giving all damage to spaceships a 0.5 wounding modifier (applied before rule #3 above, not after).

6. Divide nuclear weapon damage values by 10 before applying any other modifiers (e.g. proximity blasts)

7. When a section with armor slots is struck, re-roll each hit that hits a component besides armor ONCE (i.e. don't reroll the reroll). The attacker can also just choose to hit the armor with no penalty to the attack roll. This is particularly important because of...

8. At double cost, armor can include "reactive armor". When the actual armor component is struck, roll a d6. On a 3, 4, 5, or 6, multiply its DR by 10 against that specific hit. After each time reactive armor activates, reduce the chance of it working (to a 4/5/6, then 5/6, etc.) until it is only activating on a 6. Halve the effect of reactive armor against nuke blasts (since it is a wide area saturation). Track the reduction of reactive armor effectiveness by section (i.e. front, center, rear), not by individual armor slots.

....


If all that sounds excessive... I've run the numbers a bit. Even with ALL of those changes, a direct hit with a heavy missile is instant death. Lasers will rapidly chew you to death if you loiter in their range (they still get their armor divisor, unlike projectile weapons). A direct hit with a nuke is instant death except for extremely large ships.

Last edited by seasalt; 06-19-2023 at 01:52 AM.
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Old 06-19-2023, 02:53 AM   #2
Fred Brackin
 
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Default Re: GURPS Spaceships: Lethality reduction rules switches

These projects would always go smoother if people would go _with_Spaceships instead of thinking they have to go against it.

You want stronger defenses and weaker offenses? Great! Declare all defense tech to be 3 TLs higher than offensive tech. Or use normal offense with Cosmic Defense.

You want armor that isn't made out of normal material? That's what Hyperdense is. I think there's a force field reinforced defense in Spaceships 7.

You want Spaceships to work more like movies and TV shows? That's what "Cinematic"' is for.

You could also just take the great energizer of space combat out of the picture somehow and that's speed. This is easier if your setting is smaller than realistic "outer space" You could even start hitting "Cinematic asteroid belt" densities if you were exploring an ancient space station belt just around an Earth-like planet. Look how much Gundam is set only around Earth orbit..
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Old 06-19-2023, 04:38 AM   #3
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Default Re: GURPS Spaceships: Lethality reduction rules switches

The main thing I'd do is remove 'death' checks for reach -1 x HP, etc. A ship can then keep fighting (with penalties) as long is it has functional systems, and is rendered helpless not by pounding it until it blows up, but by knocking out the systems that let it function. If it's weapons and drives are all high energy systems, killing the power-plant will render it unable to fight or manoeuvre, for example.
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Old 06-19-2023, 06:11 AM   #4
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Default Re: GURPS Spaceships: Lethality reduction rules switches

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Originally Posted by Rupert View Post
The main thing I'd do is remove 'death' checks for reach -1 x HP, etc. A ship can then keep fighting (with penalties) as long is it has functional systems, and is rendered helpless not by pounding it until it blows up, but by knocking out the systems that let it function. If it's weapons and drives are all high energy systems, killing the power-plant will render it unable to fight or manoeuvre, for example.
Yeah, an option is to treat each component as an individual thing (in which case you may want to actually track damage, have the components do their own HT rolls to avoid being disabled/destroyed, etc), and the "spaceship" is just a collection of those things - so destroying a cargo hold has no impact on the rest of the ship (unless the ship was carrying something volatile), and damage to other systems only compromises the functioning of that system. That's not entirely realistic, but would help a lot with survivability while still making a certain degree of sense.

Of course, one of the big ways to improve survivability is to give your spaceships some degree of IT:DR, possibly justified a being a result of internal forcefields or similar. If using ablative force screens, you could also have (some of) the ship's mundane DR actually apply to the force screens as well (you can fluff this as the shields being designed to conserve energy by weakening impactors/energy to a level the spaceship's armor can handle). For Harpyias (when/if I ever get around to working on it again), my intent is to have both effects in play (the IT:DR would only apply against energy attacks, but that's the primary threat in that setting anyway), and combined with the fact combat speed in space is extremely slow in that setting (the combat is meant to be akin to WWII but IN SPAAAACE - the setting is heavily inspired by Star Wars), that should make spaceships fairly resilient. I wouldn't go with fully-independent components, but I have some ideas on how to tweak things there as well (roughly something like the individual components having their own HP and the ship itself having its own overall HP representing damage to the superstructure, but some damage to components will "leak" through to the superstructure).
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Old 06-26-2023, 04:42 AM   #5
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Default Re: GURPS Spaceships: Lethality reduction rules switches

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Originally Posted by Fred Brackin View Post

You want stronger defenses and weaker offenses? Great! Declare all defense tech to be 3 TLs higher than offensive tech. Or use normal offense with Cosmic Defense.

.
3 TL higher armor is nowhere near enough to address the problem, if (like me) you consider it a problem that armor/hit points and damage effects are so out-of-scale that most game mechanics, like component damage, damage control, etc., are pointless and will never be used since every ship will always kill every other ship with a single shot of any weapon.

I honestly feel like whoever wrote this ruleset was so desperate to avoid making it "cinematic" that they went too far in the other direction. I'm sorry, but a single shell or missle fragment should not kill a million-ton capital ship ten times over. It's not about being cinematic or un-cinematic, it's just silly. I honestly get the feeling that most of the PDF was written before the decision was made that damage dice should be multiplied by velocity.

Personally, I think it's more realistic for a large spaceship to be crippled by getting hit with a large-ish shell or missile, rather than immediately disintegrating, which is what happens in the rules as written.

Quote:
The main thing I'd do is remove 'death' checks for reach -1 x HP, etc. A ship can then keep fighting (with penalties) as long is it has functional systems, and is rendered helpless not by pounding it until it blows up, but by knocking out the systems that let it function. If it's weapons and drives are all high energy systems, killing the power-plant will render it unable to fight or manoeuvre, for example.
The damage and health/armor asymmetry is so titanic that this doesn't even make a difference. Most secondary caliber or larger projectile weapons will deal 10 to 20 times a starship's full HP on an average hit, making death checks moot. Even shrapnel from bursting shells or missiles will cause this. It's really silly.
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Old 06-26-2023, 06:18 AM   #6
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Default Re: GURPS Spaceships: Lethality reduction rules switches

Just to make certain we're on the same page, a couple questions for OP.

First off, what does your book list as the base damage of the lowest-caliber projectiles? Early printings of Spaceships erroneously had character-scale damage here, but listed it as Spaceships-scale dDamage, resulting in all projectiles doing 10x as much damage as they should. If your book lists the lowest damage as something like ndx10, this is incorrect - it should just be nd.

Next up, you keep referring to all weapons basically one-shotting your ships, but pretty much all of your examples sound like they're talking about projectiles at high relative velocities. There are options available to make point-defense beams much more effective at screening against such, which will result in most damage being caused by beam weapons - and as those start out at fairly low damage values and don't get affected by relative velocity, they're much more survivable. Would something like that work for you, or are you specifically wanting a setting where spaceships primarily fight using projectiles?
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Old 06-26-2023, 07:21 AM   #7
Fred Brackin
 
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Default Re: GURPS Spaceships: Lethality reduction rules switches

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I honestly feel like whoever wrote this ruleset was so desperate to avoid making it "cinematic" that they went too far in the other direction. y.
The rules were written by David Pulver and there is/was no one better qualified to write them.He wasn't deserate to do anything but he did start with realism as a base.

As Veryon notes the only one shot kills I ever got for whole ships were with kinetic energy weapons at very high relative velocities. In fact I did shoot a 1 million ton (SM+14) battle station with missiles travelling at 70 miles per second. Note that at that velocity a good rule of thumb has every projectile exploding on impact as if it's entire mass was made of an explosive 2000x as powerful as TNT

Just basic Gurps (nothing to do with Spaceships) has that doing over 20,000 pts of damage (2000 dDam in Spaceships).

Part of your problem in that 4e drastically lowered object HP to speed up combats. You could go back to 3e to get small-ish ships with 10s of thousands of HP.

You won't find stats for old-fashioned guns in Gurps Traveller 3e. Everyone in the setting knows that such guns are useless in space combat and the stats for them were omitted.

Arguably not omitting the guns was a mistake on the part of Spaceships but Spaceships wanted to be comprehensive and even cover magical wooden galleons shooting cannonballs at each other and Gundam-like mecha flying at low speed in Earth orbit.

For other ships and situation guns are useless. If you want a gun-dominated setting you need to shorten your ranges and lower you speeds.
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Old 06-26-2023, 08:07 AM   #8
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Default Re: GURPS Spaceships: Lethality reduction rules switches

I know one of the issues is that caliber and Ship size don't scale as they ought: A major battery at SM+15 is mounted on a 700 meter ship and fires a 56 cm shell, but a major battery on a SM+5 ship is mounted on a 15 meter ship and fires a 10 cm shell. Watch for that effecting your numbers.



I went and worked out what the guns should be here.
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Old 06-26-2023, 08:45 AM   #9
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Default Re: GURPS Spaceships: Lethality reduction rules switches

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Originally Posted by ericthered View Post
I know one of the issues is that caliber and Ship size don't scale as they ought: A major battery at SM+15 is mounted on a 700 meter ship and fires a 56 cm shell, but a major battery on a SM+5 ship is mounted on a 15 meter ship and fires a 10 cm shell. Watch for that effecting your numbers.



I went and worked out what the guns should be here.
Interesting. I'm working through this as I type, so I'm going to presume you've already arrived at most of these places.

On the plus side, your SM +9 Major Battery is a 400mm cannon that fires roughly 1-ton shells...which sounds most auspiciously like the 406mm shells of the Iowa Class. So a vessel mounting a single one of those cannons is sporting a Major Battery; if you want (say) three groups of three, you MUST downgrade to a Medium Battery so you can cluster them.

On the other hand and to your point, the Iowa class was a bit bigger than an SM +11 ship (about SM +11.5 fully loaded), but was SM +13 in length.

It probably actually winds up mounting three SM +10 gun systems, but each of those has three SM +9 guns in it.

Medium batteries are "one step down" in caliber, so the relationship holds between SpaceShips and your sheet - as it should - and it explicitly lists "up to three."

So, perfect. We have an SM +10 Minor Battery with three SM +9 guns in it. It's mounted in a ship that's SM +11.5 by mass and SM +13 by length; most of that fiddle will come down to adjusting SM for length UP for hydrodynamics and DOWN for the fact that much of the mass is just undifferentiated armor.
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Old 06-26-2023, 08:47 AM   #10
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Default Re: GURPS Spaceships: Lethality reduction rules switches

There's another thing that's not been mentioned - Force Screens. If you want space operatic combats with ships soaking big hits, they help enormously.

Another thing is that space opera-style ships tend to have bunches of guns, rather than a couple of big ones, so don't use Major or Spinal weapons.
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