Eggshells with Hammers in Psi-Wars: Contemplating Capital-Scale Damage

"I'm interested in seeing how you handle the eggshells with hammers problem" - Patron Jose
"That's not how I would see dreadnoughts fighting one another." - Patron Brett Tamahori

So, the drop of the dreadnought and my Eggshells with Hammers article sparked quite some discussion with made me stop and think and revisit a lot of ideas I had, which proved fruitful. It also proved time-consuming, and I’m still walking through the results. Balancing damage in Psi-Wars has proved difficult for precisely the reasons I outlined in my article, and it’s a problem a lot of people face. Thus, I thought by posting these musings, proposed rule changes and synthesis of various house-rules might serve as a useful worked example for others.

This is going to be a long walk through some GURPS "insider baseball."  The idea is to highlight the problems with how GURPS handles damage at large scales for the specific problem of dealing with fighters vs dreadnoughts as we tend to see in Star Wars and other forms of space opera, so read a long if that interests you!  This will be the first of, ah, a few posts.

Fighters vs Capital Ships: the Isomeric Torpedo

One of the big problems I’ve had in Psi-Wars is the difference between blaster damage and explosive damage. I’ve so far handled it by carefully limiting how much explosives I allow in my game, and then tried to use that limited exploit to make fighters pertinent in space combat. But in so doing, I’ve failed to grasp what those explosives were.

My “weapon of choice” for defeating a capital ship with a fighter has been the isomeric torpedo. I built this with the 400mm super-isomeric warhead (using some equations offered by GURB). The idea was that this was the heavy, “capital scale” weapon while the 160mm was the fighter-scale weapon. The only problem I saw with this was that nothing really prevented a craft from loading as many fighter-scale torpedoes as it would like. I would like a slightly heavier version, but I wasn’t sure how to build it.

It turns out this is unnecessary, and I didn’t understand what a 400mm missile was. A 160 mm missile is about the same size as any air-to-air missile, which is confirmed by them having about the right damage to take out another fighter. A 400mm missile is about the size of a fighter-mounted cruise-missile, such as, for example, the Popeye cruise missie. The pyramid article from which I derived it even describes it as something an aircraft might mount. So our fighters are dealing ten thousand damage with a missile that you need an SM +15 spinal mount to match.

What I perceived as “ship-mounted missiles” might be larger (so called “anti-ship missiles”), and I could create 640mm missiles and 1600m missiles to represent ship-mounted nuclear missiles and ICBMs respectively; such weapons would have 20k and 80k damage respectively.

So, if this is “too much damage,” why not just reduce the sort of warhead you’re using from super-isomeric (which is BS super science anyway) to isomeric, plasma, or even just HEX? Well, because the primary purpose of Psi-Wars is supposed to be a sci-fi setting, and I want an answer to “Why don’t we just nuke them?” which is “That’s what isomeric torpedoes are.” Worse, plasma lance missiles are highly competitive for single-target damage (a 400mm plasma lance missile deals an average of 1,600 damage with an armor divisor of 10, which means it can punch through 16,000 DR, making it better at getting through DR than an isomeric missile, even if it does less overall damage).

The problem is not the type of explosive, but the fact that explosive weapons (all explosive weapons) scale badly at these high levels. Whatever change I wanted to institute, I’d need to integrate an across-the-board rebalance of damage.

Capital Ship v Capital Ship: Mo’ Guns Mo’ Problems

One of the guiding principles behind my dreadnought design was giving them firepower more-or-less equivalent to the an isomeric torpedo; that is, something that could slice through 10k worth of DR, thus I needed about 6dx100(5) damage. These proved to be fairly small weapons compared to the whole ship, and I was able to pile on 12 of them, arranged in 6 turrets, as well as offer a mess of other guns and point defense cannons. The firepower pouring off of this thing was terrifying. But at the same time, I couldn’t give it too much DR, or it would prove to be impregnable, especially to fighters armed with smaller weapons (the 160mm torpedo), so it shouldn’t have more than 2500 DR. The compromise was to give them about 2500 DR, but to also give them tons of ablative force screen to slow down the assault.

It doesn’t make a difference though. Dreadnoughts are so big and so static that you’ll always enjoy your accuracy and a huge SM bonus, which means you can hit one of these things while it’s in orbit, frankly (in fact, if one hung over our world at 100 miles distance, like the ISS, you could casually pick it out with your naked eye). Without diving too deeply into the math: a single salvo using pessimistic rules (like adding all the guns up and treating them as a single high ROF weapon), you hit with almost every shot and you can strip the force screen with all the minor weapons put together plus a couple of hits from the big guns, and the rest of the big guns rapidly reduce it to below 0 HP in a single salvo. This is not the gigantic warship vs warship slugfest people had envisioned.

On the other hand, if you point the dreadnought at his enemy so he has DR 5000 and adjust his force screens for 30,000 DR then you get… no result. You still hit with almost everything, but you do no meaningful damage. So once again, we’re stuck with “You’re fine or you’re dead”

Thematically, I would expect that while maneuvering matters, positioning yourself so you have your most DR facing your target and he has his least wouldn’t mean you were perfectly untouched and he was a smoldering ruin after a single turn (the “dreadnought iajutsu duel”), but that you took a little damage (enough to rock the boat at least), while he lost a few important systems and the death spiral now favors you more strongly, but he could surprise you, or evade, or count on a lucky strike from one of his fighters, something. We want to see dreadnought slugfests.

A New Vision of Damage

In the real world, what is the fundamental difference between the damage dealt to a capital ship by an aircraft vs damage dealt to a capital ship by another capital ship? This seems to be the core question. How do we balance a storm of fighters with a hail of fire from another dreadnought? How can we let fighters make a difference without one-shotting a dreadnought, while also allowing a meaningful dreadnought duel?

The answer is this: there is no difference. In the real world, a fighter can equip a ship-killing cruise missile and one-shot a much bigger ship. Yes, this does keep some members of the navy brass awake at night. Why invest so heavily in giant ships if they can be easily cleared from the board? The answer for the US navy seems to be about a love affair with aircraft carriers (for a variety of reasons), and in the Empire, it seems to be the love of giant ships, but also because there must be some way to mitigate this extreme damage in space that we don’t have in the real world (nanocarbide armor, force screens, advanced construction methods, blah blah blah).

Unifying Damage

If there is no difference between a fighter carrying a torpedo and a dreadnought’s cannon, then we have the first answer to our question: they should do roughly the same damage. In my previous article, I pointed out David Pulver’s Extreme Damage article and discussed “unifying curves.” If we use his cube root for explosives for our 400mm isomeric torpedo, we come to about… 3500 damage (I want to also note that his design makes smaller explosives more dangerous, which has the added benefit of making grenades more interesting). This is the equivalent to an SM +13 major battery. That means for an SM +14 vehicle like our dreadnought, we could spare about 10% of its mass for 6 such batteries, making it roughly the equivalent to a squadron of six Starhawks carrying torpedoes. It’s actually better, because it’ll cut through DR much better: assuming 2500 DR, each torpedo would do 1000 damage, while each shot from the cannons would deal about 3000 damage, so you really need 3 torpedoes to create the equivalent of one of these dreadnought cannons, but we could find some way to allow the fighters to “attack weak spots” to keep them competitive.

The advantage here is that starfighters suddenly scale a lot better with dreadnoughts. X starfighters = X turrets on a dreadnought. If we expect a flight of 6-20 starhawks to take out a dreadnought in a single turn, then it’s fine to have a dreadnought do the same. If we expect a dreadnought to need 10 turns to take out another dreadnought, then we would expect to see 6-20 starhawks take the same amount of time. There is no difference between a capital ship and a sufficient number of fighters when it comes to damage, only when it comes to approach.

So, why don’t capital ships use torpedoes?

If starfighters, being much smaller than dreadnoughts, can use a mess of torpedoes to inflict serious damage on another dreadnought, why do dreadnoughts use much more expensive blasters when they could be using torpedoes?

I had a few answers to that question worked out: they cost more per shot than a blaster does (though still come to something like 1 turret = 1000 missiles) and I wanted to make them easier to shoot down, but that might prove very cumbersome and complicated. Worse, the way missiles work make them better for dreadnoughts than for fighters. The reason you give a fighter a cruise missile is because you want to keep your carrier over the horizon. You launch your F-16 with its “Popeye” cruise missile, it flies for a thousand miles, finds its target and launches its long-range cruise missile to hit it even further away, and then goes home. You never see the sort of thing you see in Star Wars, where the dreadnought launches torpedo-armed fighters and then also starts shooting its own weapons at the enemy ship. In such a scenario, a real world fighter/cruiser combination like a Dreadnought, if its enemy got that close to it, would probably not waste time scrambling fighters and just fire missiles.

Missiles don’t care about range, they care only about speed, size and ECM. In practice, a dreadnought is going to be impossible to miss with a missile, whatever your range, so if we treat torpedoes like missiles and we mounted torpedos on a dreadnought, not only could it mount far more (hundreds, easily, per blaster), it could fire them from very extreme distances, like even the “Remote” range that I mentioned in my dogfighting notes: a 400mm missile has a range of 1500 miles. Remember how I argued that dreadnoughts would scramble starfighters to intercept a target at about 1500 miles away? Well, it could just fire a 400mm missile to do the same, if it had them. This, by the way, is why GURPS space combat works the way it does, why “100 miles” is “point blank” for space, because you can reasonably tag a target from half a continent away with a a missile as small as 400cm, never mind something like a reactionless ICBM.

This also means that your “bombers” don’t actually need to get close at all. They would work like real-world attack craft as I described above. They would fly thousands of miles to attack someone even more thousands of miles away. They wouldn’t work like you see in Rogue One or in a New Hope where they “get close” to “land that hit” on that “small weakpoint.” And we want them to. So what’s the answer?

In every game I’ve played that featured space torpedos, from Wing Commander 3 to Strike Suit Zero, torpedoes are unguided. They are surprisingly slow moving rockets (my fighter can easily catch up to them, though it might need to activate afterburners to do so). Firing them from a long distance with a capital ship is an invitation to just shoot them out of the sky. But if you get close, you can hit them with a torpedo before they react, similar to how real-world torpedo bombers would work in WW2.

This suggests that isomeric torpedoes, in addition to moving slowly, have no guidance. This makes them good for shooting at static targets (such as planetary ones) or big, hulking things like capital ships, and explains why fighters swoop in close to hit precise targets, because being closer gives them a bonus to hit. This also means that firing a torpedo is different from firing a missile (it’s Gunner (Rocket) effectively, not Artillery (Guided Missile), but we can give them generous defaults).

To compensate, we should allow them to bypass force screens for the same reason fighters can: they’re moving slowly enough. This makes point defense and solid armor even more critical; it also means you can’t just wipe someone’s screens with a single torpedo, making it a wash, tactically.

“Why won’t you die?” Steel-cage Texas Dreadnought Deathmatch

The last piece we need is to understand why a dreadnought can take so many hits. We have a few suggestions, such as giving them more and more IT:DR, but if I’m honest, I can just tell you what I want: it’s something like we see in the ideal GURPS Spaceship battle, where most hits do no more than 10% damage, and disable system after system, so the crew is running around trying to put out fires and get their craft up and running again, and crew abandons ship not because it’s hit negative HP, but because the power core took a few hits too many and is going to go critical, or the life support was damaged. Dreadnoughts don’t blow up, they sort of get hollowed out by the sheer firepower that hits them.

Patron Michal Malus, on a discord conversation, pointed this out and suggested a rule in GURPS vehicles about damaging buildings and their “breach capacity.” The idea here is that a building doesn’t really take “damage” in the sense that an extremely powerful bullet is more dangerous than a slower bullet: both of them end up zipping through the building leaving it relatively intact, and one needs a lot of bullets, whatever their damage, to bring a building down, or you plow a mess of vehicles through it, etc. One does not kill a building so much as deconstruct it, and in that sense, he’s pretty spot on.

But rather than try to figure out how this would work in 4e, someone has done something similar for us already. My favorite author of GURPS alternate rules, Douglas Col,e proposed one in his “Conditional Injury” article in Pyramid #3/120. I highly recommend you look it up (it’s like $8, and it puts a little money in his pocket. C’mon!) but the executive summary is this: instead of tracking HP, you have a “wound threshold” and when you take damage, that the sort of wound you would suffer.

I’ve seen this sort of thing in Legends of the Wulin, and the net effect is that fighters accumulate a mess of problems rather than being fine and then being dead. For example, he might be bleeding in such a way that makes it hard to see out of one eye, and he might have a wounded leg that makes it hurt to move quickly, and his red chi might be blocked, forcing him to rely on his green and blue techniques exclusively! Such a system typically makes it much harder to land a “knock-out” blow or to finally wear your opponent down to nothing, and you need some way to track what all of those injuries would be.

This may or may not be a good idea for treating people, but it seems like a really great way to treat spaceships. Arguably, it’s what GURPS Spaceships was already trying for with its hit-location charts, its detailed injury results, it’s relatively minor penalties for being below 0 HP, etc. Let’s take a look at how it might work.

Assume that a dreadnought has 8000 HP (400 HP and IT DR), with 15,000 hardened ablative force screens, and 2500 DR. It is hit by 11 shots that deal an average of 1000(5) damage, and 9 shots that deal an average of 2000(5) damage (this is about typical of a current “knife fight” between dreadnoughts). In the old system, the 11 weak attacks would reduce the force screen to 4000 DR, and the first two big hits would reduce it to zero (and, in practice, deal a little damage as well, but let’s ignore that). The remaining 7 hits would deal 1500 damage each after DR. That’s a total of nearly 11,000 HP, which instantly drops the dreadnought below 0 HP (Though not quite killing it outright). In GURPS Spaceships, this would result in 7 disabled systems (with double-ups destroying a system).

Using Conditional Injuries, the same attack would result in 7 minor wounds. A minor wound, especially for a ship, is nothing worth concerning yourself over. It might rock the ship, you’d notice, there would be score marks on the ships, but you’d be fine. Under the base rules, these would never account for anything substantial, and you’d need to deal at least about 2500 damage before you started to see some results.

As an optional rule, we can “accumulate” injuries: after the first hit, our ship currently has a “minor wound,” and for each additional hit, we can roll HT to avoid increasing wound severity (the exact nature of those rules are a little unclear, but we can tinker with them until we like them), which means you can eventually kill a ship by dealing lots of little damage eventually. This is probably critical, as a typical fight between dreadnoughts will not be about the guy with the biggest gun winning, but about keeping as much firepower on a target as possible. If our wound increases to Major, we may have a system disabled. On another Major wound, we might have another system disabled, and so on, and since wounds “accumulate,” once we’ve lost one system, even minor damage can potentially increase (on a failed HT roll) to another lost subsystem and so on, until we have a cascade of failures and an increase into “reeling” damage.

Doesn’t that look like how you’d expect a dreadnought fight to look?

Okay, but what about fighters? If you’re going to present one system for dreadnoughts, shouldn’t you present the same system for all vehicles? Well, alright. A starhawk has 150 HP, while a fighter-scale blaster deals about 100(5) damage, and a missile deals about 400 (it gets a little more damaging in the new cubic scale, as do grenades, which is another mark in its favor). A single hit with a blaster is enough to send it Reeling, which means the vehicle is suddenly very difficult to control and has likely lost at least one subsystem. A hit with a missile is fatal: you can roll HT to see if your ship survives, but it’s probably a matter of time before it collapses completely. So the difference between standard damage and conditional injury for fighters is largely moot.

In fact, it becomes easier to handwave when it comes to damage: you know that a hit from a fighter blast is always going to take out a system: a low roll just takes out one system, a middling roll destroys a system, and a good roll might destroy the fighter outright, while a missile is a guaranteed kill. For a dreadnought, if you get hit by anything substantial, don’t even bother to roll for damage, just make an HT roll at some penalty to see if any systems were damaged, unless you got hit by something really big, like a super-weapon’s artillery blast (say, 10,000 (3) would instantly cripple a dreadnought, and on a good roll, might kill it in a single hit).

The only downside I see is that it becomes yet another new rule to learn, but I have a few ideas on how to make it easier to remember.

A Comment on Force Screens

By the book, Force Screens provide semi-ablative DR. The rational behind this is that you can diminish their protection with sufficient firepower, but after a minute (actually about 10 seconds), it will revert to normal. I find in practice that on the time scale of GURPS Action’s chases or space combat, that you might as well treat it as DR, and this can create a problem as DR tends to create binary situations of either having too little damage and doing nothing or having too much damage and instantly obliterating your target, and this is even more of a problem when we start to mix scales. By making it ablative, we allow targets to whittle away their opponent’s defenses and do some real damage, and we never really invalidate anyone’s contribution.

However, in our previous, Starfighter vs Starfighter, Starlet’s force screen didn’t do much to protect her starhawk. She took a total 215 damage, and suffered about 141 points of “wounding.” This means that the Typhoon can certainly damage the Starhawk, but we want the force screen to do something. Originally, back when I started discussing these problems in Iteration 6, I had proposed that they be hardened. Let’s make some comparisons about what would have happened to her in various models. Assume a target takes two hits each dealing 150(5) damage vs a DR 400 force screen (a 200 DR screen adjusted to defend against an attack, but only actually offers DR 80 against the attack, after the armor divisor). Simplified Ablative simply loses DR equal to the total damage done, regardless of how much it protects. Fully Hardened Ablative Simplified outright acts like a layer of HP, ignoring all armor divisors and simply taking all damage dished to it.

Conditional Injury

Screen Model	1st Shot	2nd Shot	3rd shot	4th Shot	5th Shot
No Screens	150	300	450	600	750
Semi-Ablative	70	142	215	290	365
Ablative Force Screens	70	156	255	364	481
Ablative Simplified	70	170	300	450	600
Full DR	70	140	210	280	350
Hardened Ablative	16	78	169	279	402
Hardened Ablative Simplified	16	83	200	350	500
Fully Hardened Ablative Simplified	0	0	50	200	350

Some things leap out at me. First, my intuition about semi-ablative proves correct: you might as well just treat it as full DR, as unless you really pour a lot of firepower into it, you won’t see a difference, and if you’re going to put that much firepower into it, your target is dead anyway. Semi-ablative seems a better option for armor than for force screens. Ablatie isn’t too bad! In the short term, it isn’t much different than full DR, it’s just once it runs out, then you start to see the damage racking up. Here, you don’t really notice a major difference until 4+ shots (3+ if you’re human scale). Hardened Ablative DR is actually better than full DR in the short-term: by 4 shots its indistinguishable from full DR, and beyond that it’s definitely inferior. Hardened Simplified is worse than full DR after 4 shots. Fully hardened is a little binary for my tastes, but I must admit that it makes for much easier book-keeping for big dreadnought-on-dreadnought fights. Perhaps we treat Heavy screens that way?

Alright, fine, but we’re using a new combat system. Shouldn’t that reflect this here? Let’s assume a 150 HP vehicle. What sort of wounds can we expect? Note that higher is worse

Conditional Injury

Screen Model	1st Shot	2nd Shot	3rd shot	4th Shot	5th Shot
No Screens	+0	+0	+0	+0	+0
Semi-Ablative	-2	-2	-1	-1	-1
Ablative Force Screens	-2	-1	-1	+0	+0
Ablative Simplified	-2	-1	+0	+0	+0
Full DR	-2	-2	-2	-2	-2
Hardened Ablative	-6	-2	-1	+0	+0
Hardened Ablative Simplified	-6	-2	-1	+0	+0
Fully Hardened Ablative Simplified	NA	NA	-3	+0	+0

The way Conditional Injury tends to bunch things up leads to some interesting conclusions, which I’ve illustrated with color. No screens is clearly too dangerous. While it’s a lie to say that Semi-Ablative is exactly the same as full DR, they’re very close. If we use any kind of ablative force screen, then eventually we run out of DR, which is the intention. Most collapse after 3 hits in this particular case: the only meaningful difference is whether you take a wound on that singular hit. Personally, I think I would favor Ablative, Hardened Ablative, or Hardened Ablative Simplified (which look so similar that the simplification looks like it might really help track damage). I must confess surprise that standard ablative really isn’t too bad!

Thus, I propose treating all force screens as Hardened Ablative and I would suggest simplifying the ablative rule so that all damage inflicted on the vehicle is subtracted from the Ablative DR, especially for “heavy” force screens.