What RPG has the best spaceship design system?

[Michael Thayne]

Honestly, these arguments are a good example of why I care about quality of spaceship design system, including quality of missile design system: rather than just argue about this stuff endlessly, you could actually test out the implications of various assumptions.

[Anthony]

Originally Posted by Michael Thayne

Honestly, these arguments are a good example of why I care about quality of spaceship design system, including quality of missile design system: rather than just argue about this stuff endlessly, you could actually test out the implications of various assumptions.

No, what that does is test the quality of the RPG's physics engine. You want to do the math using actual physics and then fix the RPG if it gets the wrong results.

[Michael Thayne]

While there are some aspects of this debate where it's quite clear what the laws of physics say, at the end of the day we are talking about fictitious weapons systems whose effectiveness cannot realistically be deduced from first principles. In harder-science settings, the technologies are often inspired by ones that already exist today, but presumably 100+ years in the future they'll be a lot more developed, and anyway the real world technologies are often highly classified and untested in real combat conditions. That makes the idea of judging space combat games by whether they match the One True Way of space combat deducible from first principles ridiculous, all we can do is ask what sort of combat paradigm falls out from a given set of postulates.

So sure, given fuel type and fuel-to-payload ratio we can calculate a missile's delta-V, but questions like, "will military planners in the 23rd century decide the advantages of liquid fuel rockets are worth the downsides when it comes to small missiles?" and "how much armor should a missile have given the current state of point-defense technologies?" are not things that can be easily derived from first principles.

[Michael Thayne]

Getting back to the original point of this thread, I'm wondering if it's worth buying CORPS and the related Guns, Guns, Guns! (I already bought CORPS VDS, lol).

[Anaraxes]

Originally Posted by Fred Brackin

I'll admit that I've never considered an ion thruster missile but I think I know why. You'd have to be firing at something with an even lower acceleration.

Or simply less endurance. Space is big. That'd be the military SF version of "The Cold Equations".

But that's my point. The ion thruster probably has more delta-v than a chemical rocket. But you don't typically think of using them as your missile drive. The chemical rocket has a much better power output, even if it has less delta-V, so it can run down a target in some cases. Just comparing delta-V totals isn't all you need to know to decide whether a missile intercepts its target. (The only time that really works in the situation in the first paragraph: more than enough time to make up for any acceleration deficit, and low enough endurance that the target exhausts its delta-V in that time.)

Originally Posted by Michael Thayne

at the end of the day we are talking about fictitious weapons systems whose effectiveness cannot realistically be deduced from first principles... That makes the idea of judging space combat games by whether they match the One True Way of space combat deducible from first principles ridiculous, all we can do is ask what sort of combat paradigm falls out from a given set of postulates.

So why did you ask in the title for "the best" spaceship design system in an RPG, and add later that you were particularly interested in the system's handling of kinetic-kill missiles? That seems to be coming at the question from a very Atomic Rockets perspective.

As it happens, I agree with this point. The spaceship design system supports the setting. The setting, however, is a bunch of prior assumptions made by the author/designer to give them the sort of RPG that they want. That has nothing to do with real physics -- and it also has nothing to do with starting with a set of rules and seeing what implications fall out of them. Settings are designed top-down, not discovered by experimenting with a ruleset. With this mindset, the question is backwards. The question that exists is just "do these rules imply something radically different from the setting assumptions?". If kinetic-kill missiles (possibly targeting planets with near-c kilograms) aren't intended to be a thing, then the lack of them in the rules isn't a reason not to consider that system "best". The system is doing its job.

It's also very difficult to compare the best-ness of two different systems, as they'll have completely different goals, and even if one is a little better than another at supporting its environment, you can't take that system and plug it into a different setting, as its assumptions and results are different from that setting's assumptions. The design systems aren't portable across settings, so there's not much point in trying to rank them by global bestness. You might ask "which of these three systems has spaceships that feel the most like Star Wars movies?", but that's not going to help you with your Traveller or Honor-verse or Aliens game.

[Fred Brackin]

Originally Posted by Anaraxes

Or
Just comparing delta-V totals isn't all you need to know to decide whether a missile intercepts its target. .

I didn't actually say that. i don't really understand why you keep trying to make your point by distorting what I say.

[RogerBW]

Originally Posted by Anaraxes

As it happens, I agree with this point. The spaceship design system supports the setting. The setting, however, is a bunch of prior assumptions made by the author/designer to give them the sort of RPG that they want. That has nothing to do with real physics -- and it also has nothing to do with starting with a set of rules and seeing what implications fall out of them. Settings are designed top-down, not discovered by experimenting with a ruleset.

A similar example: everyone now knows that an unfettered reactionless drive means great big kinetic impactors. But we have settings with reactionless drives where that isn't how wars are fought or how terrorism happens, not because they have supertech defences but for reasons so obvious that they are never mentioned (possibly, in the real world, because they predate the general realisation that this would be a problem). If you run a game in such a setting, you just have to say to your players "that is not a thing here".

[Michael Thayne]

Originally Posted by Anaraxes

So why did you ask in the title for "the best" spaceship design system in an RPG, and add later that you were particularly interested in the system's handling of kinetic-kill missiles? That seems to be coming at the question from a very Atomic Rockets perspective.

As it happens, I agree with this point. The spaceship design system supports the setting. The setting, however, is a bunch of prior assumptions made by the author/designer to give them the sort of RPG that they want. That has nothing to do with real physics -- and it also has nothing to do with starting with a set of rules and seeing what implications fall out of them. Settings are designed top-down, not discovered by experimenting with a ruleset. With this mindset, the question is backwards. The question that exists is just "do these rules imply something radically different from the setting assumptions?". If kinetic-kill missiles (possibly targeting planets with near-c kilograms) aren't intended to be a thing, then the lack of them in the rules isn't a reason not to consider that system "best". The system is doing its job.

It's also very difficult to compare the best-ness of two different systems, as they'll have completely different goals, and even if one is a little better than another at supporting its environment, you can't take that system and plug it into a different setting, as its assumptions and results are different from that setting's assumptions. The design systems aren't portable across settings, so there's not much point in trying to rank them by global bestness. You might ask "which of these three systems has spaceships that feel the most like Star Wars movies?", but that's not going to help you with your Traveller or Honor-verse or Aliens game.

Because there are a bunch of ways to judge the quality of an RPG rules set that aren't "is this the One True Way?" Things like internal consistency, whether the rules match the fluff, etc. I'm not necessarily opposed to hand-waving away missiles, though a lot of attempts to do so are painfully clumsy. For example, in Transhuman Space, lasers always hit, meaning the only "missiles" in use are heavily armored, hundred-ton monstrosities. And the thing is, the "lasers always hit" feature of the setting gets consistently applied regardless of what the target is. This is a big improvement over GURPS Spaceships, which has a "missile shield" design switch for buffing point defense that has no effect on lasers interact with things that aren't what the game calls "missiles".

Originally Posted by RogerBW

A similar example: everyone now knows that an unfettered reactionless drive means great big kinetic impactors. But we have settings with reactionless drives where that isn't how wars are fought or how terrorism happens, not because they have supertech defences but for reasons so obvious that they are never mentioned (possibly, in the real world, because they predate the general realisation that this would be a problem). If you run a game in such a setting, you just have to say to your players "that is not a thing here".

The trouble here is internal consistency. RPGs with reactionless drives often do have ramming rules, and even cases where "great big kinetic impactors" have been used in the setting's story. Telling your PCs "yeah, the bad guys did use a great big kinetic impactor that one time, but you're not allowed to just because" is rather unsatisfying IMHO.

[Polydamas]

Originally Posted by Michael Thayne

Honestly, these arguments are a good example of why I care about quality of spaceship design system, including quality of missile design system: rather than just argue about this stuff endlessly, you could actually test out the implications of various assumptions.

I thought you said that you were looking for a design system which reflected setting assumptions? A realistic spaceship design system or spaceship combat system will not be like spaceships or combat in any corporate franchise and will probably not be fun to tell stories about. We don't need a design system to tell stories about mine trucks or container ships or airliners, just a rough understanding of their capabilities from the perspective of someone who wants to get from place to place.

In my view, a spaceship design for Star Wars or Star Trek should completely ignore Newtonian or Einsteinian physics. Ships in Star Wars travel at the speed of the plot, so formalize that and have a way of deciding who wins in a chase between starships Nothing in Star Wars is a logical extrapolation from anything, its a mash of tropes and inspirations.

[Michael Thayne]

Originally Posted by Polydamas

I thought you said that you were looking for a design system which reflected setting assumptions? A realistic spaceship design system or spaceship combat system will not be like spaceships or combat in any corporate franchise and will probably not be fun to tell stories about. We don't need a design system to tell stories about mine trucks or container ships or airliners, just a rough understanding of their capabilities from the perspective of someone who wants to get from place to place.

In my view, a spaceship design for Star Wars or Star Trek should completely ignore Newtonian or Einsteinian physics. Ships in Star Wars travel at the speed of the plot, so formalize that and have a way of deciding who wins in a chase between starships Nothing in Star Wars is a logical extrapolation from anything, its a mash of tropes and inspirations.

I don't know how you formalize "ships travel at the speed of the plot"—though if you've seen it done I'd be very curious to know the details. I am somewhat leery of "well this is how it is in fiction" arguments—fiction can get away with more hand-waving than RPGs because in an RPG the rules need to be clear enough to present players with meaningful choices. Certainly it's possible to throw everything we know about physics out the window, but traditional sci-fi likes to maintain a pretense that real-world science isn't wrong per se, just incomplete. Throwing that assumption out tends to get you steampunk or science-fantasy more than traditional sci-fi.

I would also note that come of the challenge here comes from trying to ape tropes that come to us from either the Age of Sail or early 20th century naval warfare. Adopting a more Cold War / post-Cold War frame might work better for telling interesting stories with realistic physics. Just surviving asymmetric threats could be challenge enough, while great-power war could be a threat that lurks just off-stage because everyone knows it probably means mutual destruction.