Immutable Time Travel


I read Homestuck for the first time around the same time I rewatched Terminator (1 and 2), and it got me thinking about using travel through immutable time as a game concept. The upshot of immutable time is that it lets you send the players throughout time without having to figure out how the minor and major changes they make would alter the future (which, in any kind of non-predestined time, would be a lot). The drawback is that you instead have to figure out how to keep them from changing anything. The following is an overview of how this kind of time travel would work (largely patterned on how it works in Homestuck, so minor spoilers for that if you plan to read it), and includes several elements to try to keep the scope of attempting to change the past manageable within a game framework. (This is presented as in-character advice from a time traveler.)

1) Time is internally consistent

Time travel doesn’t actually let you change anything. Circumstances will conspire to negate whatever change you’re attempting to make. Killed your grandfather before your mother was conceived? Turns out your grandmother never mentioned her husband’s twin and his untimely murder. Attempt to travel back and tell yourself something on a day you know you didn’t meet yourself in your own timeline? You’ll never actually get to the meeting due to seemingly random accidents, or something will happen to erase your memory of the meeting in the past, or some other bullshit.

Your best bet, when time traveling, is to know as little as possible about any events you’re trying to interact with. Your ignorance doesn’t mean that things aren’t objectively true (you still can’t actually change anything, from the point of view of someone who does know what happened). But at least you won’t know for sure whether what you’re trying to do is futile.

2) Information ignores paradox

Sometimes information-based time loops become stable with no true cause. Brought yourself back the same formula for cold fusion that you gave yourself when you were young, and told yourself to pass on once you discovered time travel? No problem. Pulled a time-travel Oedipus and became your own father, creating a Y chromosome from nowhere? Gross, but not a paradox.

Maybe the information comes from the zeitgeist. Maybe it comes from the gods of time fucking with us. Nobody knows for sure. Maybe someone will pass the secret of how it’s possible through a self-generating time loop at some point.

3) Matter, however, can’t get stuck in a time loop

Matter is much easier to degrade than information. Reality seems to be fine with the secrets to a better watch coming from nowhere, but the watch itself needs a provenance. If a time traveler gives you an object, you cannot give that same time traveler the same object to take back to you. You can take it apart and make an identical duplicate, as long as the matter for the duplicate came from somewhere real (or you can just find where the item originally came from, send that one back, and keep your version). It’s all down to a loop being infinite: a piece of finite matter stuck into it would gradually erode.

Don’t even try to mess with this, it can get really wonky, really quickly. Note that a really obnoxious exception is that immortal, ageless living things can actually come from nowhere, since they regenerate their bodies with new matter from the environment; they can just expect memory loss somewhere along the line before they start the loop over again.

4) You can fork a timeline, but you absolutely shouldn’t

In extreme circumstances, it is sometimes possible to change something. Despite the implications in rule one, there isn’t actually some kind of omniscient deity keeping you from changing things. Sometimes events seem weirdly contrived to try to keep you from making alterations, but if you had a god’s view of the situation it would all make sense as a series of interlocking causes. Reality’s defenses against changing the past are passive, and if you really, really set your mind to changing something in a way you know for a fact is a change, you often can.

Don’t do that. You are no longer a resident of the prime timeline if you do. Back in reality, you made a different decision, and things proceeded as they always had. You and the entire reality you forked off are now doomed; the universe doesn’t have enough energy to keep forks going for very long. If you stay there, you’ll start to notice that entropy is on overdrive, and everything quickly begins to fall apart, including your own cells. You can time travel back, usually as the special paradoxical exception that got you to reconsider making a change in the prime timeline. Then you’ll likely die. Gruesomely.

5) Because reality is sturdy, it’s worth it to try things

You will not step on a bug in prehistory and totally change the course of evolution (unless you already did). Your modern flu will not start a new plague that wipes out Europe (thought it might have started a documented one). You will not accidentally give Genghis Khan the future tech he needs to start the industrial revolution centuries early and conquer the globe (though he might have you burned as a witch). Really, unless you’re trying to fork a timeline by enacting something you know is a change, the worst things that can happen are that attempting to change things gets you hurt or killed with no alterations, or you find out that you were responsible for something that already happened anyway.

Want to save a loved one that died in an accident? Just be ready to leave a convincing replacement corpse and it might all work out. Need to find out a piece of long lost information? Wander around asking questions in your future clothes and it’ll be fine, in the grand scheme of things. Timeline predestination is freeing, in a way: if it’s possible to succeed, then you always did, if it’s impossible, then you’ll find out pretty quickly, and if you fuck up grandly along the way, the future was always a product of that catastrophe.

Just keep the rules in mind, try not to learn anything that makes you certain you’re going to fail because you already did, and experiment. A time traveler with guts and cunning can accomplish a lot of marvelous things… that were always destined to have happened.

Reliving the Day

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I’ve always been interested in the idea of running an RPG in the vein of Groundhog Day or Stargate‘s time loop episode. I recently watched Day Break (which looks like it’s now on Hulu instead of Netflix), which had a lot of cool ideas for how to actually pull it off in a way that makes sense for an RPG (some of these are minor spoilers for the show).

Elements of the Premise

Your game should feature at least a few of the following elements:

  • The PCs start the day in peril: By the time the loop starts in Day Break, the main character has already been framed for a crime. This creates immediate tension every day, as he has to keep ahead of law enforcement while investigating. The PCs shouldn’t be able to just take a day off to recuperate or train without planning and a chance of failure, or the game might lose its sense of danger. Thus, starting them off with some kind of personal and dedicated threat keeps the game from losing momentum.
  • If you keep your memories, you keep your injuries: The counterpart to not having your brain reset is not having the rest of your body reset either. You can’t just kill yourself when you get frustrated and restart the day, like in Groundhog Day, and you also can’t just try something stupidly dangerous over and over until it works out through dice luck. This also implies that you’re aging, so you don’t want to spend years stuck in this loop even if you could otherwise become a small god of the place you’re trapped. And if you actually die in the loop… well, your significant other is going to have to wake up next to your decaying corpse for quite a number of loops, and you wouldn’t want to inflict that on a loved one, would you?
  • There are multiple people aware of the loop: Obviously necessary for multiple PCs, both Day Break and Stargate‘s episode feature potential allies in others that want to escape the loop. Beyond the other PCs, there may be unpredictable factors also aware and changing things. Just when you think you’ve figured out all the angles on an event in the loop, it changes and you don’t know why, until you realize there’s another aware actor in the loop with you. Maybe the whole premise of the game is that once you’ve been trapped in a loop, you’re aware whenever other people nearby get trapped, and you have to help them solve their problems to restore time.
  • You can change the loop slightly via great effort: One of the most interesting elements of Day Break is that he can sometimes improve his situation by repairing a dysfunctional relationship: on the subsequent loops, the loved ones in question are more likely to help him, even if they don’t remember why. You could retain this kind of mechanism for a personality-focused game, or even build in more overt mechanisms based on the rationale for the loop. Effectively, though, pursuing side quests is actually rewarding. Rather than being a waste of something that will just reset again tomorrow, they can generate rewards that make the main plot easier to complete.
  • The playing field is constrained: Groundhog Day has its blizzard, Stargate traps them in the command center and world they’re traveling to that day, and Day Break has all of the local law enforcement on the lookout for a fugitive. Coming up with a similar method for your game limits the amount of tangents the players can get up to, and how much information you have to create beyond the original scope.
  • The number of iterations is limited: Either because the characters are slowly aging, because they’ll go insane from too many repetitions, or because the very process is destructive if allowed to loop for a nebulous “too long,” the players can’t just decide to sequester themselves for relative years to learn whatever skills they think are necessary. Because your players will definitely want to pull a Phil Connors and use the opportunity to max out their skills before even attempting to solve the main plot if you let them.
  • The way out of the loop is easier to identify than to solve: It may only take a couple of iterations of digging to figure out the likely source of the time loop. Day Break has to unravel the conspiracy that framed the protagonist and Stargate has to stop the machine that’s causing the loop. This creates an objective, and now the game is about figuring out how to obtain the objective. Perhaps the obvious objective wasn’t the whole story, and securing it just reveals the real core behind it all, but at least there was always an obvious goal for forward progress (and there should only be one or two princess in another castle moments anyway).

Best Practices for Running the Game

Once the elements of the premise are nailed down, there are a few tricks to make running such a thing possible:

  • Establish the prototypical day in great detail: You need to know exactly what happens if the PCs stay out of the way, down to the minute if necessary. For major characters, you may even want to map out their movements during the day both on an area map and on a relationship map. The former lets you have serendipitous events where the PCs happen to encounter an NPC unexpectedly just by virtue of being in the right place at the right time. The latter allows you to note when NPCs cross over and think about what happens if the PCs have interacted with one NPC (e.g., if NPC X gets delayed meeting with NPC Y, what will NPC Y do instead of his normal actions? If NPC A encounters the PCs, will she tell NPC B about it at their meeting?).
  • Create lots of intersections that may only become apparent on repeat viewings: That relationship map is especially important because peeling back the layers of relationships is one of the key elements of interest in a game like this. How many iterations will it take before the PCs realize that the guy they keep saving from a building fire was actually a key member of the conspiracy that someone is trying to kill via arson? How long until they realize the day regularly ends on a parent being held hostage because that parent was how the conspiracy got interested in the PCs in the first place?
  • Have a good map of the area with an easy way to determine the time it takes to move around: This is especially useful if you can put major NPC routes on it without making it too busy to read, but at the very least you want to be able to give the PCs reasonable travel time notes between locations. A lot of the game may boil down to figuring out a sequence of things they do to give themselves an advantage or just save innocent lives, and it’s important to know how long that takes. When the PCs finally figure something out that involves another location, can they get there in time from the last thing they wanted to do?
  • Always keep track of the time: Maybe obvious, but you should be able to make it clear to the PCs what time it is, and if they get separated you should flip between them in as much of a real time manner as makes sense for your scenes. Having a fake clock you can make constantly visible would be a big help, even if it’s just something you’ve made out of card stock and brads like in kindergarten.
  • Take copious notes: The only way to do this thing in any way at all that feels like the TV shows or movies that include it is to feel free to improvise, but make detailed notes of what you did. If the players want to go somewhere at 10:45 AM that they’ve never gone and you had no plans for, feel free to invent some local color, but you have to write it down so the players will see the same thing if they go there again. When the players change something, and you decide how that affects the rest of the day, it should generally do the same thing over and over until they change something else.
  • Don’t be afraid to end a session early: Sometimes, the changes that the PCs have started to make regularly should have some pretty detailed follow-on effects. Don’t be afraid to stop the session so you can prepare a revised relationship map for the next time that assumes the common changes the PCs tend to make. You can only be in the moment for improvising this kind of thing so far before you need time to really look at the various permutations and make sure you’re not forgetting a logical consequence or changed movement of an NPC in the new possibility space.

Serial Numbers Filed Off 1: Dissolution

Comments Off on Serial Numbers Filed Off 1: Dissolution

Originally posted September 2007

So yesterday I had the concept of taking Scifi/fantasy films, swapping their settings, and repackaging them as RPG campaigns. Let’s see how the first one goes.

In the reign of King Aric IV, the evil artificer Skanath began his endgame. Long at war with one another, Aric IV and his rival, Elessar II, escalated their border wars until they had proved they were equally matched. Each turned, unbeknownst to the other, to Skanath for a golem army. Skanath obliged, placed his golems in crucial positions in each kingdom, and then turned on all sides, obliterating their militaries in a single master stroke. All in the kingdoms that were not killed were forced into slavery, serving at Skanath’s pleasure as he built more and more golems to pacify the neighboring countries.

We rebelled. Skanath’s armies were mighty, but the human spirit prevailed, all inspired by the great paladin Conner. We threw down the walls of Skanath’s tower and dragged him before our leader, but Skanath only had a smile of contempt and hollow laughter. Behind him, a great sigil had been inked, and our wizards sensed a mystic violation of the very boundaries of time. Skanath had sent back a mighty iron golem, cloaked in illusions, and with a single command: hunt down and kill the leaders of the resistance before they were even born.

There was enough power in the rite to send one more through, and Conner, though I understood not his wisdom, sent me back. I have come to you now, in the era of ailing King Aric III, to protect our future. We may strive to keep the states of Aric and Elessar from their costly war and from their alliance with Skanath but, above all, we must stay hidden from the golem that was sent back to destroy all of our hope. For if Conner and his lieutenants are killed, our future is slaves forever.