Designing an apocalypse to order

[Michael Thayne]

I'm designing a sci-fi setting, and want to apocalyptic war in the backstory. The reason for this is (1) to reduce the importance of Earth relative to interstellar space colonies (settled with the help of "precursor" FTL tech founder under the ice of Phobos), and (2) kneecap technological progress for 200 years while the space colonies have time to grow. Alien force-screen tech served as an enabler for "torch drives" (drives that are simultaneously high-thrust and high Isp, though "high Isp" is still only on the order of about 30,000 seconds in this context). Otherwise technology is stuff like below-human-level AI, fusion, lasers used as space weapons but not able to totally replace slugthrowers, and similar.

Nuclear weapons seem well-suited to the result I'm going for—among other things, after 200 years the radiation should mostly have faded on Earth. But I'm contemplating adding other stuff. I'm tempted to add "alien nanoplagues" to the tech assumptions above. Or purely earth-made bioweapons. There's also the possibility of using fusion drives to slam comets into Earth—hitting the US eastern seaboard with a comet or two (of carefully chosen size) is tempting both in terms of "America is the great fallen civilization people look back to" and ensuring the dominance of the metric system.

But I'd like input on fine-tuning the details so that they're actually consistent with my desired result. As opposed to say, "Earth becomes uninhabitable for a generation" or "Earth is Mad Max land for three centuries or more".

[Kale]

If you plan on having your PCs actually visit Earth at some point (or your campaign starts on Earth), then consider using After The End to work out some of the finer details of the apocalypse. That book has an "Apocalypse designer guide" that will really help work out the nitty gritty of how things ended. If the PCs probably won't visit Earth, or will spend very little time on it, then you can have vague myth and rumors reach the PCs ears with little detail, so you won't need to work so hard on writing up the apocalypse. You can just hand wave it away as "Nuclear War between world powers devastated most urban areas. Hardly anyone even remembers how it started anymore."

Tangential idea: somebody discovered another precursor device that disrupts precursor shield technology. It was used to make some fusion drives catastrophically fail in the war or a terrorist attack. This either contributed to how the war started, or how the war escalated to the point where nuclear weapons were used. The disruption tech was mostly lost in the war.

[khorboth]

What about... bombardment?

So, Earth becomes more and more dependent on orbital resources, most notably power stations tethered to the tops of space elevators. The workers on these platforms, though, are treated poorly. Eventually, tentions boil over and there's a public massacre.

A sympathetic group of astroid miners decides to shoot a bunch of asteroids at Earth in retaliation. They initiate dozens of strikes and make demands promising to reveal coordinates once said demands are met. They are not taken seriously and the facility is destroyed as an example.

Months later, an asteroid comes streight out of the sun, where instruments weren't looking and would have a hard time spotting it. The impact is devastating to population and production.

Some of the others are found, but not all. The population lives in fear. Impacts happen every 6 months to 10 years. Compounding this economic damage is that almost nobody of wealth stays on Earth. Those who can flee, do. Thise who stay can't afford to build any kind of viable detection or deflection system and every time recovery seems to be on the way, destruction rains from the sky.

[Fred Brackin]

Originally Posted by Michael Thayne

, after 200 years the radiation should mostly have faded on Earth".

Not really much of an issue. There isn't really that much lingering radiation and it wouldn't cover that much of the Earth's surface if there was.

I'd seize upon the inspiration of the moment and ahve earth devastated by natural plagues with the surivors of those shooting at anyone who comes near. The space colonies would survive better because they were easy to isolate and the smaller (but higher tech) populations were easier to genetically engineer.

Tell your PCs they were all born with Resistance to Disease +8 and you won't realy have to explain that much.

[Irish Wolf]

"Slamming comets into the planet" would be more a K-T Event sort of thing, I would think, rather than the more, ah, genteel apocalypse you seem to have in mind.

Perhaps a limited nuclear war, like the 1995 World War Three from Twilight: 2000 or the Great War of 2077 from the Fallout franchise, although you'd need to find a reason why it fizzled. (One idea I've been toying with: the nukes were all launched as in an all-out exchange, but it turned out that they had a high failure rate while in storage so only about a quarter of them actually exploded. This would be enough to devastate large urban centers and major military installations, leading to a collapse of centralized government, while still leaving enough people and salvageable technology to permit Earth to reach out again in a mere two centuries. Frankly, two of the things preventing this in Fallout are the radstorms, which don't seem to conform to our laws of physics, and the occasional direct intervention of the Zetans, who I assume have their own reasons for fearing humans aside from Zetans' innate cruelty and viciousness.)

[khorboth]

Originally Posted by Irish Wolf

"Slamming comets into the planet" would be more a K-T Event sort of thing, I would think, rather than the more, ah, genteel apocalypse you seem to have in mind.

We are admittedly well outside my expertise, but wouldn't that depend upon the mass and velocity of impacting objects? We do get impacts every so often with varying levels of damage, so something between "moderate crater" and "everyone dies" seems plausible. Indeed, documenteries love to measure the strength of meteor impacts in atomic bomb equivalents.

[Kale]

Originally Posted by khorboth

Some of the others are found, but not all. The population lives in fear. Impacts happen every 6 months to 10 years. Compounding this economic damage is that almost nobody of wealth stays on Earth. Those who can flee, do. Thise who stay can't afford to build any kind of viable detection or deflection system and every time recovery seems to be on the way, destruction rains from the sky.

You know, that's part of the anime "Cowboy Bebop": An FTL gate near the moon had an accident and shattered the moon. Decades later the Earth is still randomly bombarded with moon chunks still in orbit. This economically and infrastructurally destroyed the Earth; the other colonized planets in the solar system consider it a backwater planet because it is essentially populated by refugees that can't escape off world.

[thrash]

Originally Posted by Michael Thayne

There's also the possibility of using fusion drives to slam comets into Earth...

You might want to check the math on this one. In a setting where an Isp of 30,000s is "high," you'll either need a very lucky find (e.g., like C/2013 A1 and Mars) or years of prep. A fusion torch large enough to move a continental-scale disaster comet won't be stealthy. Even if one were able to hide the drive plume, the suspiciously trending non-gravitational forces on its orbit would flag it immediately as under control and invite retaliation.

Or, perhaps, this is what touches off WWIII: lack of intel on who is controlling the comet leads to paranoia, recriminations, and then a wet-squib war when attempts to deflect it fail.

[ak_aramis]

Originally Posted by thrash

You might want to check the math on this one. In a setting where an Isp of 30,000s is "high," you'll either need a very lucky find (e.g., like C/2013 A1 and Mars) or years of prep. A fusion torch large enough to move a continental-scale disaster comet won't be stealthy. Even if one were able to hide the drive plume, the suspiciously trending non-gravitational forces on its orbit would flag it immediately as under control and invite retaliation.

Or, perhaps, this is what touches off WWIII: lack of intel on who is controlling the comet leads to paranoia, recriminations, and then a wet-squib war when attempts to deflect it fail.

I think the bombardment would/should be more of the, "You orderd 5 MT of steel? Here, airdropped as 5T darts, all 1 million of them." More of the "Drop what we have" rather than accelerate a single large mass.

[copeab]

Zombie apocalypse, aka use of weaponized rabies that goes terribly wrong.