The Forge Archives

Preface: This is the latest thread in the GroupDesign project, tentatively titled "Schrodinger's War," a collaboratively designed game about incorporeal "Archivists" who jump through time and space, possessing human hosts to alter history, constantly forced to balance the welfare of their individual host with their objectives for humanity as a whole. The most concise (if somewhat out of date) overview of concepts occurs in the thread Nailing mechanics; older threads are indexed here. But reading through all these past threads is by no means required -- all Forge-folk should feel free to participate.

A lot of our earlier discussion struggled with the idea of a "Nemesis" : a Really Bad Event that the time-travelling player-characters would seek to forestall as the long-term objective of a campaign. We've also poked at the edges of how in hell we're going to model the effects of changing human history without getting hopelessly tangled in chains of cause and effect. Now Doug Ruff, one of our frequent contributors, has come up with a new take on The End of the World as We Know It -- including a concept on how to change history that involves thinking backwards in time from effect to cause:

To let Doug speak (via PM) for himself:

Quote from: Doug Ruff
Wiping Out Humanity

I've asked Sydney to kick off this thread open discussion over something I raised in Tobias' most recent thread - The Pillars of Tobias.

OK, here's the pitch: I want to wipe out the human race, and I need your help.

Why? There are a couple of reasons why I would like to see this as a core (or at least, favoured) option for the game:

1) The most dramatic way to present a Nemesis within the setting is to let it win. "At some point in the future, the human race is wiped out. Now it's up to you to do something about it." This provides an immediate issue for the players to address.

(I am presupposing a time-travel campaign for this to work, and I think that if you explore the more recent Groupdesign threads, you will notice that time travel is an implicit part of the concepts. So let's make it Core.)

2) I've been thinking a lot about how changing events in History has an impact on the whole of the Host Time Tunnel (if you are new to this project, please check out this thread, or substitute "timestream" whenever I say Host Time Tunnel or HTT.)

One of the real problems with dealing with the HTT in any "realistic" (for which, read "Simulationist" perhaps) way is that major changes to early history could completely invalidate changes made later on; if I prevent the fall of the Roman Empire, will there even be a Napoleonic army? Or a National Socialist Party?

We've discussed before the option to say that major events are "overdetermined" and therefore resistant to change. I'm going to suggest a refinement of this view, which was inspired by Tobias' Impact mechanic (which assessed a person's impact on the future - I appreciate that this is a fairly sweeping generalisation, but this is how it inspired me, dammit!)

I would like to suggest that events are "overdetermined" by their impact on the future of the Host Time Tunnel. This is a complete reverse from the original theory (which is that events are overdetermined by what came before) but I think it works (and works better) within a time travel campaign.

In other words: under the "old" theory, the rise of Nazi Germany was "overdetermined" by the economic and political circumstances that led up to the election that placed it into power. In the new theory, the rise of Nazi Germany is overdetermined by all the people who died after they came into power.

This has an automatic consequence: as a rule, the further back you go into History, the harder it is (generally) to change things.

But, given the exponential rate at which the human population grows, how is it possible to change anything at all within this model? If humanity reaches the stars and colonises the galaxy, there is hardly any difference between 3000 BC and 1945 - events within both eras are cemented into place by their mpact on the countless billions of humans who inhabit known space - and if this expansion continues indefinitely, then Archivists would be all but powerless to act on known history.

Therefore: my conclusion is that humanity doesn't make it that far. In order for the Archivists to have any significant power at all, something must happen to end the History that they work with. For example, a nuclear war or a cometary strike - whatever it is, something that humanity doesn't recover from, ever.

Unless the Archivists do something about it.

And this is where the real Difficult Choice comes in: if the Archivists do manage to save Humanity and allow it to flourish, they weaken in their power to change things (as there is more "future" to overdetermine and lock down events.)

So Archivists may not want to rescue humanity, or at least, not to do it until humanity is in a fit state to progress. Or Archivists may wish to concentrate on the spiritual development of those Hosts that do exist before the catastrophe, in order to develop as many of them into Archivists as possible. Or Archivists may just want to keep their powers, and let the catastrophe take place.

Please comment, on the overall idea, and also on whether it should be brought into the mechanics somehow (which is likely to make it "core.")

Ahhhh... yer all just sissies.

Human race.  Feh.  Destroy the universe.  Then say that the human race would have been the key to preventing said destruction if they had not been wiped out by clever little Nemesis before undertaking the destruction.

Then the entire Great Library is a last-ditch effort run at inverse-time-dilation within the last two objective seconds before the collapse of everything.  This equates to some subjective period of time in the HTT (like, oh, say, eight sessions of play) during which the players must rescue the human race and explain (in so rescuing) what value or power humanity has that makes them the unique threat to the Nemesis.  Then your epilogue is describing how humanity saves the universe.

The reason you don't futz around with Nazi Germany is that you can't predict the consequences, and you don't have the time to do a massive historical survey of those changes.  You've got a fixed period of time.  If the players want to waste that precious time having the GM improvise alternative histories then screw 'em, and screw the universe too.  Indeed, the mechanics can reinforce that by saying every time they change the time-stream they reduce their own knowledge skills about all future periods of time.

So, anyway, that's my hardball contribution.

Okay, so I'm going to be a super-sissy. Instead of wiping out the universe, or (merely!) the human race, I'm going to suggest a "soft" version of Doug's idea, that gets similar dilemmas less dramatically:

If events are "locked" (determined) in history by their significance on what happens afterwards (as opposed to by their causes), or even if we embrace traditional sci-fi time-travel paradoxes, then the key event for the Archivists is the event that brought Archivists into being in the first place. If the Archivists' own existence is the byproduct of, or entangled with, some awful negative event (Nemesis), then you get a dilemma: The more you mess with history, the better you make things for humanity, but the more you reduce your own power to affect history -- ultimately perhaps to the point of causing yourself not to exist.

But, heck, I'm all for eliminating the human race -- albeit extinction doesn't have to be purely physical (comet strike): I think self-inflicted extinction due to moral/social causes has far more bite.

I'm not a huge fan of time travel as a device...but I like Doug's take on overdetermination.  

Essentially, the more future things would be screwed up by whatever changes you're making to Now...the harder it is to make meaningful changes to Now.  Thus, the farther back you go in time, the greater the volume of stuff there is after that time that resists you.

That's a perfect built in Difficulty modifier for the game.  Franz wants to jump over the moving train...how hard is it?  Who cares what the actual physical difficulty is in jumping over a train...Franz can always zap out to the future and zap back to that exact moment with a pair of anti gravity boots ala Bill and Ted and "Remember the garbage can".  Giving players a nearly unlimited ability to bounce around through the time stream essentially makes any action virtually 100% automatic success...Zap back to 1947 from 1999 and in order to foil some Nemisis plot you need to make an impossible shot?  No problem.  Fortuneately in your copious spare time you zap back to 1990 and became a super expert marksman so 9 years later when you zap back to 1947 you can make the shot no problem.

In other words...task difficulty no longer matter.

Alls that matters then are two factors.  1) how far back in the time stream are you (farther back is harder), and 2) how invasive of an event are you doing (i.e. something minor that might have ripples that aren't immediately obvious vs. killing Abraham Lincoln before he gets elected president).  No matter what task the characters do, that's your source of difficulty.  All other task related difficulty can be explained away by time-wavium.

The first source of difficulty should be counted back from "Extermination Day"...the "day" humanity gets wiped out (probably measured in eras or some other mushy unit of time for practical game purposes).  Every time you successfully thwart a Nemisis Plot, you delay the inevitable by some amount (I'm picturing a very Gamist-esque victory conditions table for each scenario).  As the E-Day gets pushed farther into the future by the players' success...difficulty becomes increasingly hard for their characters...since humanity now survives longer, there's more stuff ahead of them, no matter where they are in the time stream than there was before.  If they fail, the reverse happens.

As an example of the interesting things players could do...when faced with a HUGE Nemisis plot that if defeated could push the human future another 100 years out, players might go back and screw things up for humanity on purpose (maybe going back and undoing some of their own earlier successes) moving humanity's demise 40 years closer.  This would make the difficulty they confront for the big plot lower making that plot easier to foil and so net them 60 years.


If one wants something a little more crunchy than auto success at any task difficulty, you can set task difficulty on some numerical scale which would add to time stream difficulty.  Players could turn any task into an auto success by spending X number of years training or developing some gizmo etc, where X equals the task difficulty to be overcome.  The years would be spent on the character sheet as if they were some metagame mechanic and listed into the characters "history".

1664-1668 AD spent 4 years studying with the finest fencing master in paris.

2058-2064 Received doctorate in genetic medicine from John Hopkins University.

In order to be helpful the era the years are spent in must correspond to the "skill" being mastered.  When the player has spent all available years (obviously years spent studying with the Priests of Horus in 3500 BC will be of limited value in 1970s Viet Nam), he can't do this any more...UNTIL...the player's successes push E-Day into the future...freeing up additional years to spend.

Or something like that.

Quoting Doug  Ruff:

QuoteWe've discussed before the option to say that major events are "overdetermined" and therefore resistant to change. I'm going to suggest a refinement of this view, which was inspired by Tobias' Impact mechanic (which assessed a person's impact on the future - I appreciate that this is a fairly sweeping generalisation, but this is how it inspired me, dammit!)

I would like to suggest that events are "overdetermined" by their impact on the future of the Host Time Tunnel. This is a complete reverse from the original theory (which is that events are overdetermined by what came before) but I think it works (and works better) within a time travel campaign.

In other words: under the "old" theory, the rise of Nazi Germany was "overdetermined" by the economic and political circumstances that led up to the election that placed it into power. In the new theory, the rise of Nazi Germany is overdetermined by all the people who died after they came into power.

This has an automatic consequence: as a rule, the further back you go into History, the harder it is (generally) to change things.

But, given the exponential rate at which the human population grows, how is it possible to change anything at all within this model? If humanity reaches the stars and colonises the galaxy, there is hardly any difference between 3000 BC and 1945 - events within both eras are cemented into place by their mpact on the countless billions of humans who inhabit known space - and if this expansion continues indefinitely, then Archivists would be all but powerless to act on known history.

So, what you're working with is the metaphysical concept that more witnesses to an event strengthen it as reality. The more human beings alive who know that an event is historical, the harder it is to change, so very early history is rock solid.

I'm not sure I think that model will really help make things easier, as I expect players will want to work within the mentality of the time period they are in. Because of the scarcity of surviving records, ancient histories actually are percieved as more flexible in that mindset. The explanations for dragons and so on as a part of forgotten history. That leads back to the past being easier to manipulate, and larger ripples from those changes and so on and you're back to paradoxes.

Some stories have made this a non-issue by treating the "real world" history as the right one, and the efforts of the players all lead toward ensuring this reality, but that's irritating, especially when you give the players access to time travel, and then tell them they'll have no appreciable effect.

Other similar but hopefully less buzz-killing approaches are to handle the big events, the ones that everyone knows about as fixed, while the smaller events that go unknown to the masses are your wiggle room, the places where you can effect change.

For example: The Hindenburg crashed and burned on May 6th 1937. What caused it, who was on it, why it burned and wether or not it was a "good" thing for the timestream that it burned are all up in the air (as far as the greater mass of beings know.) The players might need to change the situation, not in it's outcome but in it's causes so that the agreed on result matches with the Archivists' plan.

That casts the Archivists in a different light as well. Less the saviours of the world, more like the intelligence agents of Allied forces in WWII, trying not to give away that they had broken the Enigma codes by acting on the information too well, and letting soldiers and people die as a result.

Hope I'm not just muddying the waters here. Time travel in a game is one of my favorite concepts. I can't have watched all those years of Dr. Who for nothing.

Quote from: TonyLBAhhhh... yer all just sissies.

Human race.  Feh.  Destroy the universe.  Then say that the human race would have been the key to preventing said destruction if they had not been wiped out by clever little Nemesis before undertaking the destruction.

Yep, that's pretty hardball!

Of course, in the "standard" HTT continuum, the Host universe has always been destroyed (just skip to the end of the tunnel...) so I'm going to assume that your idea means that the Archivist part of the universe is also going to go kaput. Correct me if I'm wrong.

And again, that's hardball, and I like it. I can imagine a bunch of Archivists who have spent thousand, or millions of years in Archivist-Time exploring and tinkering with History in the HTT, then *bang* they now have a deadline.

Not sure if I would like this to be the only way to play it, but I think that the "Universe goes boom next Tuesday" scenario really ought to be in somewhere in the final cut. Nice one, Tony.

Quote from: Sydney FreedbergIf events are "locked" (determined) in history by their significance on what happens afterwards (as opposed to by their causes), or even if we embrace traditional sci-fi time-travel paradoxes, then the key event for the Archivists is the event that brought Archivists into being in the first place.

Nice point, and one which I hadn't anticipated - if I understand correctly, this is referring to the possibility that, if events are determined by their future consequences, that changing anything in the future of an event could reduce it's impact, thereby making it more subject to change.

However, if Archivists are making lots of changes, doesn't this "overdetermine" the fact of their creation yet further? In other words, if Archvists are responsible for so many changes, doesnt this make their genesis more certain? I woul be tempted to rule that Archivists stand outside of the normal causal flow, and leave it at that - but I want to hear more.

Quote from: Sydney FreedbergBut, heck, I'm all for eliminating the human race -- albeit extinction doesn't have to be purely physical (comet strike): I think self-inflicted extinction due to moral/social causes has far more bite.

I think that the joy of it is that you can choose any of a number ways to end the world, all it has to do is end... leaving us with plenty of optional settings to play with. Including historical ones - who's to say, for example, that the Black Death couldn't have killed off the whole world population?

PS I've been thinking about the limits of Archivist power, and one of my working assumptions is that Archvists can only possess humans, and only human action has the potential to change the HTT - everything else is deterministic. This stops pre-History changing in a way that would prevent the evolution of humans, for example.

Now, this also stops Archivists from making changes to pre-History, and accidentally (or deliberately!) from wiping us all out. Now, what if Hosts managed to invent a "time machine" based on wholly scientific principles? This could be phenomenally dangerous - time traveller goes ack to the Jurassic to take some dinosaur pictures, accidentally changes History in a way that prevents humans from ever being born. Now, an Archivist couldn't do this, because of "overdetermination", but maybe Hosts aren't bound by the same rules. This could also be an Archivist reason for not saving the planet - let them die before they do any real damage!

So... I know you guys are pretty far into this development, but let me pose one basic question:

Is the core of the game the ability to play in times that we know about? I.e., is the fun aspect of playing this game that you can play in Roman times, or during a world war, etc.?

If the answer is "not necessarily," one way of doing it, which would avoid a host of issues, is to set the alterable time in our future, but the past of the Archivists. I.e., Archivists are from 3000 AD, they jump back to 2100, 2200, etc. You can make it chronological, so that the characters actually write history as the players play. The GM would need to think about some consequences in the time between sessions, but making it up is a lot easier than figuring out which events did and did not occur.

Because if the goal is to change history which we are familiar with, that would be seriously hard to simulate, as was pointed out before.

Alternatively, I thought when this game was first discussed (and I was mostly lurking) that the Archivists were supposed to gather knowledge, not change history. That might keep the ability to go to known times intact, as the interference is going to be minimal.

Anyway... just some thoughts. This is one heck of an ambitious project, with everyone's standards being high and all.

Ralph, yes, this difficulty curve is exactly what I'm looking for - either as a sole determination of difficulty, or as a modifer.


Gains, welcome!

Quote from: gains
So, what you're working with is the metaphysical concept that more witnesses to an event strengthen it as reality. The more human beings alive who know that an event is historical, the harder it is to change, so very early history is rock solid.

Close, very close  and this is exactly how we would have handled this before. My suggeston is that instead of the perceived effect, we estimate the actual effect on the future.

For example, we don't know who invented the wheel, or when and how, but the sheer impact of the invention overdetermines it.

The main crossover is that heavily witnessed, and remembered, events correlate quite highly with high impact events, especially in the modern age.

The rest of your post fits right in, though. If you're playing at the detailed history level (as opposed to Tony's more epic scale suggested earlier) then it's easier to change the smaller details of an event and work "in the shadows".

Quote from: xenopulseSo... I know you guys are pretty far into this development, but let me pose one basic question:

Is the core of the game the ability to play in times that we know about? I.e., is the fun aspect of playing this game that you can play in Roman times, or during a world war, etc.?

I don't think that it is "core" as in "required", but I think that the system has to be able to support it. And yes, it's a tough one to crack...

If I recall correctly, gathering knowledge was a core part of the game fairly early on, but the gaining of knowledge had tactical value, as it helped to either "lock down" an event through observation, or allowed an Archivist to know how best to make the right changes. Does this help?

I see.

Well, the only other comment I can make is that it may be best to have the Nemesis plot be removed from great historical events. The plot could be subtle and hidden, and take place in the shadows of these events. But if the big events are overdetermined, Archivists will not be able to change those, so cannot achieve a victory there. Or if they did, every major change needs to be taken into account for future development. If the Nemesis actions happen in more secret ways, the big picture future could remain virtually the same, while the underground development of the Nemesis plot and the Archivist development has changed.

I.e., introduce a completely different, hidden strand of history that is interwoven with, but independently alterable from, the known major history.

Quote from: gainsSo, what you're working with is the metaphysical concept that more witnesses to an event strengthen it as reality. The more human beings alive who know that an event is historical, the harder it is to change, so very early history is rock solid.

Nicely put. Hence the title "Schrodinger's War," a reference to Schrodinger's Cat: Is it alive? Is it dead? Quantum physics says it's both and neither until you intervene -- which is what this game, on a cosmic scale, is all about. But actually, I'd take it even further:

Since the start, we've been calling our game's protagonists "Archivists," and defining them (sort of) by their quest for knowledge. This is just stating baldly what others have toyed with implicitly before, but why not tie that quest directly into the Schrodinger determinacy issue (which is a refined version of the old "if a tree falls in the forest and nobody's around....").

If an event's observed, then it's locked into history; if it remains unobserved, then that part of history can be changed -- that's what we've been going with. Well, maybe it's not just any human being's observation that matters. Maybe only the Archivists count: In other words, if the player-characters (or their NPC archivist rivals) have ever observed an event, that event indeed happened; but if they don't know about it, it's up in the air until they intervene to determine that bit of history.

Heck, you could even merge in-character and out-of-character knowledge by saying what bits of history are observed/determined and therefore true depends on what the players themselves know about history and speak up about at the gaming table. Thus a group of historians will have much tighter constraints of "what is determined" than a bunch of beer-and-pretzel gamers -- and each group will probably produce a game more to its liking in the process.

Wow- SWEET concepts between Ralph, Doug and Syd!
Doug - I really think you're inverse concept really captures an essence of history that few have really captured , really eliminates a lot of the temporal headaches.

I'm really liking the concept of the Dark Archivist from earlier, and the Nemesis could tie into this yet.
Something just snapped to mind (maybe just a possible way):

The 'Archivists' came to being though a kind of temporal mishap, a device that shouldn't exist sends the group (or two?) into the 'non-time' Archivist time. The one faction seeks to use their new power to alter event X, fictional or historical, but because of Doug's inverse effects the events are difficult to change as is (which could help scale the events to the sessions players want). The mucking of time, in the end, is what destroys humanity. The players have the options of stopping the other party or stopping the device from coming into existance (assuming Doug's idea the Archivists are removed from causality- if successful, they try to access the device and it fails).

Warning: LONG post coming up. :)

After re-reading my own post, I saw that I make a lot of references to my Pillars post. This is not an attempt to drag the very valuable thoughts in this thread over there and convert them to what I already have. I just want to show where I dig this post most, shed some light on the similarities, etc. :)

Quote from: Doug1) The most dramatic way to present a Nemesis within the setting is to let it win. "At some point in the future, the human race is wiped out. Now it's up to you to do something about it." This provides an immediate issue for the players to address.

I think this is good - it ties an important concept into setting/mechanics, like we want. In the Pillars post, I am a little soft on what creates urgency - I mention some ways in which it could exist, but this 'ending' things is good. 2 'alternatives' I wanted to leave the door open for are:

1. - group-competition play - where different players represent all the Archivists in existance, and they're pushing their own agenda (you could say they're all each other's nemesis). This because of contracycle's valid comments on 'reactionary' play. On the other hand, people do well with limits, guidelines, restrictions to be creative within.

2 - smaller-scale adventuring - say you're only interested in the 'wild west' period like in my Pillars Post. In this case, Nemesis could actually be something smaller you're all striving for - like the destruction of several Indian Tribes, etc.

Quote from: DougI would like to suggest that events are "overdetermined" by their impact on the future of the Host Time Tunnel. This is a complete reverse from the original theory (which is that events are overdetermined by what came before) but I think it works (and works better) within a time travel campaign.

Yes! In fact, this is something I've put in my game as well. Quoting from the Pillar thread:

Quote from: IAll of SpaceTime is connected by a great Field. Events that are well-known and had big impact have many far-reaching ripples in this field (like a big stone thrown in a pond) and are harder to change. There are, however, unobserved points with a disproportionate impact on history and Passions – these are the points at which an Archivist may most effectively make his mark.

From this point I arrive at one of the same issues Doug runs into - exponential population boom as humanity swarms out over the galaxy. I solve it by slapping a logarithmic scale on things, called Importance. Doug solves it by ending the universe. I think both things are possible in combination. Perhaps even Nemesis cannot overcome humanity at some scale of importance - perhaps pushing back the timeline enough is the only thing that matters.
(Note that this means some protection may need to be extended to ancestors of Great People, like I've mused before).

I'd say both the past AND the future make their impact. To creatures that live totally outside (or perpendicular) to the HTT, there is no need to look at 'before' or 'after' in a conventional way - other than to acknowledge that the HTT is chopped at some definate endpoint by Nemesis now. To overcome that, you could basically act at any point.

If we take a 'chopped' timeline, say at 3000 AD, we have a piece of 'human history' of say 10000 years. Something happening around 2000 BC will have had a very long influence by 1000 AD over a small population, something happening around 2800 AD will have had a short influence by 2850 AD over a much larger population.

I'd appreciate a 'same possible impact' system, because I think it allows quite naturally for 'subtle historian' play as well as '2 fisted action' play.
Also, gains mentions 'wiggle-room' events. These I call Schrodinger Points in my Pillars post (more correctly, in my last addition to that thread. They're only called "unobserved points with a disproportionate impact on history and Passions" in the initial post.  And yes, you could act in the future of an event (Pillar, probably, in my lingo) to weaken the impact that event had.


Ralph mentions  some interesting things as well:

Quote from: RalphIn other words...task difficulty no longer matter.

Alls that matters then are two factors. 1) how far back in the time stream are you (farther back is harder), and 2) how invasive of an event are you doing (i.e. something minor that might have ripples that aren't immediately obvious vs. killing Abraham Lincoln before he gets elected president). No matter what task the characters do, that's your source of difficulty. All other task related difficulty can be explained away by time-wavium.

I ran into this though/conclusion at some point as well. And into some of the gamist/crunchy resource-management, spend time to train, etc. things  associated with it. It removes (some of) the spotlight from the posession aspect/mechanic, though. I want to 'solve' this issue by making humans (Hosts) important through the Passions they themselves have and the fact that humans, basically, are the agents that can change the HTT (I'm in agreement with "let's not whipe out pre-history".) It's hard to find the balance of where spotlight should be, what kind of play is generated, etc. Maybe I'm trying to capture too many thing, ladening me down.

'Research' or 'Training' seem like perfect candidates for pool(s) to me. Do an amount of preparation, build your pool, when you think it's enough, go do your thing (and spend your pool, since every situation's different).

And to Sydney's last comments about the combination of in- and out-of-character knowledge - this is one of the reasons why I let the players set the Passions and Pillars themselves - I imagine a group of historians might be quite interested in a taking their area of expertise and placing their timeline and important events in it.
(Or perhaps they'll laugh at it, say 'screw it', chuck back a beer, and parachute out of bombers over a burning Berlin, tommyguns in hand.

In the game, that is.)

Quote from: TobiasI wanted to leave the door open for... - group-competition play - where different players represent all the Archivists in existance, and they're pushing their own agenda (you could say they're all each other's nemesis).

I think this is entirely compatible with ending the world, actually. I'm reminded of the Avalon Hill boardgame Republic of Rome, where each player controls a different Roman faction striving for control -- even up to the point of waging civil war against each other -- but if they don't collaborate at all against outside threats like, say, Carthage, the game mechanics bring the whole Republic down. In other words, you can have player-Archivists all bitterly opposed to each others' agendas for the future but also well aware that if they all thwart each other and no faction wins, then the future of humanity is extinction.

And now, because I care a lot about including moral extinction as well as physical extinction -- because I find the end of human life on earth less horrifying that human life continuing forever without any of the aspects of humanity we value -- I'm going to suggest an alternative nightmare, but the logic takes a while to get me there, so everyone bear with me....

Quote from: George OrwellHe who controls the present, controls the past; and he who controls the past, controls the future.

That's from 1984, the book with the bleakest ending I've ever read, bar none. In that world, humanity as a species still exists, obviously, but a totalitarian regime is steadily, and successfully, erasing all the things that define humanity as a quality: love, sexual desire, individuality, etc. What is more, the regime is constantly re-writing history, destroying old records and planting new ones; and the longer the regime remains in place, the more of the past is, effectively, destroyed.

Now, if the Importance of a historical event is determined by its causes, all this Orwell stuff is irrelevant. But if we apply Doug's model, where the Importance of an event is determined by what subsequent history it affects, it's absolutely relevant: It means the Importance of an event can be, retroactively, destroyed.

It doesn't take a totalitarian superstate to do this, either. It just takes something that blocks the transmission of information, and thus influence. The first Qin Emperor (the guy Jet Li is going after in Hero) tried to burn all Confucian writings when he united China, and in general to wipe out any history of the time before his rule: He failed, but much was destroyed. The Christian mob that destroyed the Great Library of Alexandria lost us whole volumes of Greek literature. The European settlement of the Americas wiped out entire cultures through disease -- sometimes without any direct contact, as with the mound-builder culture of the Mississippi valley -- so that almost no heritage remained, either in terms of descendants or culture. And plenty of cultures have self-destructed or otherwise vanished: The Easter Island culture, or the prehistoric Indus Valley civilization about which we know basically zero (anyone but me ever even hear of these guys?). And even in Doug's hypothetical "humanity reaches the stars" future, it's quite possible that a colony descended from, say, Tibetans will know nothing about and be totally uninfluenced by anything in the history of the 20th-21th century West.

{EDIT to clarify: This is an "all roads lead to Rome" theory of historical causation, in a sense. For those Tibetans orbiting Algol, it doesn't really matter whether Russia or Americans got to the moon first, or even that Werner von Braun developed big space rockets for the US instead of for a victorious Nazi Germany; all they care about is that somebody, sometime got humanity into space.}

In short, something can be a big, big deal at the time, and for centuries afterwards; but its legacy can be erased or forgotten, and its long-term importance can thus be zero. (Even chaos theory helps us here: Yes, tiny causes can have big effects, but also over time big causes can have no effects.) If all means by which the past can influence the present are destroyed, then that bit of the past ceases to matter, which means there's nothing stopping you from changing it. Go back in time if you want, convince Euripedes to change how his plays end, or intervene in some Mayan civil war so that Smoking Jaguar defeats his cousin Leopard Mirror instead of the other way around: The plays got burned at Alexandria anyway, the Mayans were wiped out, so nobody will ever know the difference.

All of this means you don't need to wipe out the human race at some future point to give Archivists freedom of action to mess with history. All you have to do is wipe out history: If all humanity lives under a dictatorship like that in 1984 where the past is constantly rewritten, or (at the opposite end of the spectrum) in some libertarian consumerist nightmare where nobody remembers anything older than last week's commercials, then History Is History.

In this situation, most if not all of history doesn't matter anymore (maybe the one strand of legacies and events leading to the Nightmare Future matters, but everything else is effectively erased) -- which means Archivists can change it. But of course, as Archivists change history for the better, they allow legacies to be passed down, which means it gets harder to change history.

In short:

The Nemesis is a future where the past no longer matters because nothing from the past has been passed down. The Archivists are fighting for a future where the past matters.

That's a terrific concept Sydney. And actually increases the importance of the term Archivist. Is it someone who investigates history to try to reinforce their present, or someone who looks to break it down.

I had a story idea years ago about a company developing time travel and then going back to discover that they didn't really exist. That the events that led up to their lead researcher's birth didn't happen, that the company was owned by different people and completely mundane in the years leading up to their great discovery.

So, they went to work ensuring their own existence.

Never finished it, but it seems significant now.