Using time travel as an in-game tool

[Creamsteak]

You could adapt the Aetherco's Continuum game concept of Fragmentation. Make them aware somehow that, if elements change from the timeline they know, there must be a direct cause-and-effect back to an explanation of how it deviated, and WHY IT WASN'T DIFFERENT THE FIRST TIME THEY WENT THROUGH IT. In other words, say the Fireball from Heaven happened, because they said it did. They have a required future (Continuum calls it a "Yet") to make this thing happen. The longer they wait to make this thing happen, the more fragmented their existances become. They find it harder to accomplish actions, they have memory lapses, etc. As their bodies become fragmented along all possible outcomes. As soon as they make it happen, their "Yet" is fulfilled, and they are restored.

Yets could even extend to death! Let's say they know they die in a certain battle. They can do whatever they want through the time travel, but in the end they MUST return to that battle to die. If they die before they die, then it fragments their very existance to smithereens!

Definitely a good point there. Thanks Henry.

Edit: This, right?: http://www.aetherco.com/continuum/

 

[Timeboxer]

I must admit that the one thing that worries me about time travel is the entire Sound of Thunder situation -- you go back in time, kill a butterfly, and then far far in the future everything's changed.

So I think if I were to run a time travel-based game... hmm. I'd probably plunder the idea I've seen in several sci-fi short stories -- that time does not like to be changed, and tries to be static. (Like the Phoenix Gate in Gargoyles.) Perhaps, for instance, if you go back in time and attempt to fireball someone to death who needed to do something "important", another mage would "coincidentally" be there and counterspell you at that exact moment. You can go into the past or future and do all you like, but the timeline will converge toward the same essential history regardless of what you do, and paradoxes and so on are simply smoothed over.

So, in order to effect your will on time, you have to spend Temporal Karma Points or something -- which makes time a bit more pliable. The more points you spend, the bigger the potential change, and the farther-reaching the effect. And, most importantly, it makes what you do "stick". With the occasional artifact and so on, that should work out okay. (I'm also vaguely thinking about KP as a magical component, kind of like XP, to send your spell into the past or future.)

And if you ever shatter time completely, well, you can always have your heroes try to put it back together, a la Terry Pratchett's Thief of Time.

 

[Tom Cashel]

Every story about time travel makes up its own rules. You should decide on yours before the campaign starts. The players will come up with all sorts of head-scratchers if there aren't any ground-rules.

I'm currently running a D20 Modern campaign, Wings of Icarus, in which the PCs acquired a TARDIS in the first episode. My original idea was a kitchen-sink, wild and wooly, anything goes, time-hopping sort of campaign. Since then it's become more focused on the PCs histories and their lack of memories regarding certain villains...but they'll still have access to the TARDIS. (And coincidentally, the campaign relies somewhat heavily on Call of Cthulhu and Delta Green.)

In my game, we ran up against the "genre expectations" problem. They found a TARDIS with a semi-sentient computer running it, and figured that it could do just about anything.

PC: "Computer! Analyze this future device!"
Computer: "Uh...I am a time machine. My circuits are devoted to time travel, not analysis of unknown devices."
PC: "You can travel through time and space but you can't tell me how this gizmo works?!"

I decided to have the Hoffmann Institute "analyze" the TARDIS for several sessions, while I decided on my ground rules.

A couple resources were very helpful to me in deciding exactly what was possible and impossible regarding time travel, timelines, paradox, hard and soft loops, etc. They are:

Online TARDIS manual (especially the Laws of Time, principles of time travel, etc.)
GURPS: Time Travel

Some ideas that come to mind:

If you're going to allow the PCs to "buy" strange events that will later be fulfilled by their future selves, what is the mechanism by which they monitor events across time? How will the future selves know that a "debt" needs to be paid? Will they have fun spending years and years ensuring that a secret door opened in their past? What if they fail? Does time revert to the original event and start a new, alternate timeline (and coincidentally cause the loss of several levels)? Or is that the time for a Group Shrug? If there are no hard and fast rules against paradox, why don't the villains go back in time and kill the PCs as children? And then the PCs arrive just a few seconds earlier to stop them? And then the villains go back a generation earlier and try to kill the parents of the PCs? And the PCs follow them? If time travel/manipulation is a force in the game world, why hasn't some BBEG gone back to the dawn of time and stopped humans from ever evolving? Why hasn't a future villain come back to kill the PCs when they are 1st level? Why doesn't being saved by your future self put you into a time-loop?

I'm not trying to annoy, but you're opening a huge can of worms. It's a good, tasty, exciting, head-spinning can of worms...and fun too! But my advice is to try to know the answers to as many questions as you can before the game starts, and set some ground rules.

 

[Chaldfont]

This might be a good thing to read: http://en.wikipedia.org/wiki/Time_travel. It outlines many different ways fiction has dealt with time travel. I especially like 1.2 or 2.1 universes (scroll down the wikipedia entry to see what I mean).

You could drive the PCs nuts forcing their future-selves to fulfill past-self requests. Don't the future-selves have better things to do than travel back in time and kill kobolds for the past-selves? Conflicting priorities would be fun to play with: "We have to kill the beholder that threatens to destroy the kingdom but we REALLY have to go back in time to make sure we survive the orc invasion 10 years ago! If we don't, we will cease to exist!"

Another way of introducing time travel would be to do it at a smaller scale. Use the video game concept of saved games. Give each PC a limited number of Time Orbs that, when crushed, erase the last x hours/minutes/rounds. This could be really fun in a combat: Crush a time orb to "do over" the last 1d4 rounds. Use one on round 6 to undo the savage coup de grace suffered by the held fighter--but wait--now we have to redo round 4 when the wizard got lucky on his fireball and rolled high damage!

Here's another idea: the future-PCs have returned to stop, by all means necessary, the present-PCs from making a dire mistake. Don't reveal the identity of the enemies until it's almost too late ("Crap! I disintegrated myself!")

Play the campaign backwards. Start the PCs at 15th level and work back through time and levels.

Man, now I want to play a time travel campaign!

 

[RangerWickett]

The only way this could work with a villain is if the villain time travels too. He can make sure his identity remains hidden, and he can undo events that would ruin his plans.

You could use an approach from the video game Chrono Trigger. Time streams run parallel, and there are distinct eras that don't overlap. What constitutes a time stream varies for each traveler, but if I were to use my campaign, it might look like this:

Timestream One: Prehistory. Powerful entities rule a world that is barely formed, where planes overlap.

Timestream Two: Ancient History as heroes are trying to find gods to protect the world from demons.

Timestream Three: Old History when a demon tricks nations to go to war, which results in a warlord conquering the world.

Timestream Four: Recent History, when the warlord died and people fought to seize lands of their own, with magical doomsday devices being trotted out.

Timestream Five: The Present. The plane of Time has been disrupted, and the plane of Spirits is fractured as the dead from different eras interact.

Timestream Six: Far Future One. After a long dark ages, nations are finally beginning to emerge. The PCs from the present are like, what? Dark Ages? Crap.

Timestream Seven: Far Future Two. The Renaissance begins, and people begin to discover all the ancient secrets of the world, unearthing an immortal evil.

Timestream Eight: Far Future Three. That ancient immortal evil has been defeated, but nations are at war, one nation possessing strange metal warships.

Timestream Nine: The End of Time. A group of villains are trying to resurrect a fallen god, but to do so they must revive an ancient creature that died to create the world. Only the main villain in charge of the operation knows that to do so, they must undo time, and try to rewrite it. Only this plane will be rewritten, so they intend to hide on an adjacent plane.


Now, in each of the nine era, events move forward at their own pace. Once you visit an era, you can never go back to an earlier time of that era. This of course raises the question of how the PCs are influencing themselves. Well, the only possibility is that they make it to the end of time, and are able to rewrite bits of history. It's okay if the party doesn't solve the problem right away, because if they screw up and die, well, the whole world will be torn to pieces by the villain.

One key thing here, though, is that some things can exist independently of time. If a creature is truly immortal, it can travel back in time to become its earlier self. Matter traveling through time is not the issue, since everything balances out in the end. What is the problem is information.

Unlike matter, knowledge can be created easily, but it is very hard to destroy. Thus, information can only be gained from another time if you forget something from your current time.

Each character needs to write up a list of about twenty important things they know, of who they are and where they're from. Rate them in three levels of importance - 10 trivial, 7 important, 3 vital. When they want to know something, they have to trade away something else of equal value. If they go beyond this limit, they forget the last thing, which is who they are. And then, unable to help themselves, they become undone.

And of course, the climax of the campaign is dependent upon a character willingly letting himself be undone so he can save everyone else.

 

[jmucchiello]

The party is looking for an artifact in a dungeon. The fact that my present self is undertaking this quest means my future self has also undertaken the quest and completed it. So I ask for information from my future self - what is the best route to take, where are all the traps and ambushes, what monsters are where, etc etc.

Except your future self knows that there are some traps that must be set off in order to succeed at the mission. But he doesn't know for a fact which ones they are. Maybe there are clues in the bottom a few pit traps that don't appear unless someone FALLS into the pit. Maybe future future you has told future you not to answer the call for help because in a future future not going through that dungeon as was done the first time is a critical blunder with ramifications future self can't see. Maybe future self has had this revelation before and knows better than to interfere unless it is dire.

 

[Creamsteak]

I must admit that the one thing that worries me about time travel is the entire Sound of Thunder situation -- you go back in time, kill a butterfly, and then far far in the future everything's changed.

Ah, I think I know the story your talking about. Kurt Vonnegut wrote it maybe?

Yes, I think that treating time travel like that (which does make sense) would be impossible for my human brain to do. Maybe if I had a few hundred million dollars worth of computers to run simulations, but sadly I don't (and I don't think my players would wait around for it either).

So I think if I were to run a time travel-based game... hmm. I'd probably plunder the idea I've seen in several sci-fi short stories -- that time does not like to be changed, and tries to be static. (Like the Phoenix Gate in Gargoyles.)

Ah yes, I remember that cartoon. Actually, that Pheonix Gate might be a good basis for the artifact or whatever I choose to use as the catalyst.

Perhaps, for instance, if you go back in time and attempt to fireball someone to death who needed to do something "important", another mage would "coincidentally" be there and counterspell you at that exact moment. You can go into the past or future and do all you like, but the timeline will converge toward the same essential history regardless of what you do, and paradoxes and so on are simply smoothed over.

I'm thinking that certain locations, events, people, and objects will follow this sort of rule. Other objects might not react that way though. For instance, perhaps the "artifact weapon" that was meant to be used to destroy some evil plane-hoping chronomancer has absolutely uncanny "luck" at avoiding being changed by time. Attempts to move it in and out of time result in strange circumstances and absolutely improbible coincidences.

So, in order to effect your will on time, you have to spend Temporal Karma Points or something -- which makes time a bit more pliable. The more points you spend, the bigger the potential change, and the farther-reaching the effect. And, most importantly, it makes what you do "stick". With the occasional artifact and so on, that should work out okay. (I'm also vaguely thinking about KP as a magical component, kind of like XP, to send your spell into the past or future.)

I'm thinking of keeping Karma points secret from the players. That way theres no micro-managing of it. It should be a meta-game concept, on the same tier as a DM managing challenge ratings and encounter levels. That's my opinion, at least.

And if you ever shatter time completely, well, you can always have your heroes try to put it back together, a la Terry Pratchett's Thief of Time.

Oooh... a Pratchett reference. I'll have to look at that one for sure.

 

[Creamsteak]

Every story about time travel makes up its own rules. You should decide on yours before the campaign starts. The players will come up with all sorts of head-scratchers if there aren't any ground-rules.

Yeah, that's why I'm hoping that some of the enworlders here can really throw some wrenches into the spokes. So I can try and prevent that from happening at the table.

I'm currently running a D20 Modern campaign, Wings of Icarus, in which the PCs acquired a TARDIS in the first episode. My original idea was a kitchen-sink, wild and wooly, anything goes, time-hopping sort of campaign. Since then it's become more focused on the PCs histories and their lack of memories regarding certain villains...but they'll still have access to the TARDIS. (And coincidentally, the campaign relies somewhat heavily on Call of Cthulhu and Delta Green.)

In my game, we ran up against the "genre expectations" problem. They found a TARDIS with a semi-sentient computer running it, and figured that it could do just about anything.

PC: "Computer! Analyze this future device!"
Computer: "Uh...I am a time machine. My circuits are devoted to time travel, not analysis of unknown devices."
PC: "You can travel through time and space but you can't tell me how this gizmo works?!"

I decided to have the Hoffmann Institute "analyze" the TARDIS for several sessions, while I decided on my ground rules.

Sounds like good stuff.

A couple resources were very helpful to me in deciding exactly what was possible and impossible regarding time travel, timelines, paradox, hard and soft loops, etc. They are:

Online TARDIS manual (especially the Laws of Time, principles of time travel, etc.)
GURPS: Time Travel

Thanks very much for the links.

Some ideas that come to mind:

If you're going to allow the PCs to "buy" strange events that will later be fulfilled by their future selves, what is the mechanism by which they monitor events across time?

I'm not sure about how you would monitor events. I know that the basic element will be that time travel is made possible by something. That same thing should be able to show changes based on how things are going. Perhaps, when things start to get screwed up, it maybe starts to suffer visual changes like color, cracks, or such. I could use some ideas in this direction though.

How will the future selves know that a "debt" needs to be paid?

I'm thinking of using intuition and puzzle-solving problems. For instance, as in one of my examples above, if they found the same magic item twice (the exact same item, one from the future and one that they naturally came across), they would learn this through an identify spell. Thus, forcing them to solve which item is the "new" one and which is the "old" one. Perhaps it's simple (such as a partially used wand), or vastly more complex.

Now, when they actually try to call for help from there future selves, they will KNOW that they need to answer that call when it comes in. That should be the easiest sort of problems to solve. But it won't necessarily be convenient.

Will they have fun spending years and years ensuring that a secret door opened in their past? What if they fail? Does time revert to the original event and start a new, alternate timeline (and coincidentally cause the loss of several levels)? Or is that the time for a Group Shrug?

I know I don't want to "revert" time. Level progression and such should always continue normally. If they screw something up, they have to try and fix it. They could perhaps find that the timeline they exist in now is different from the one they started in, but for whatever reason I think the PCs need to be immune to these changes to at least a certain degree. However, they should still suffer concequences. There have been a bunch of ideas in this thread already with those though. Fading away, missing items, suddenly losing use of there arm, a party member being dead (which would be a great way to deal with a missing player on a particular game night, come to think of it. They have to change time so that the character doesn't die, and such).

If there are no hard and fast rules against paradox, why don't the villains go back in time and kill the PCs as children? And then the PCs arrive just a few seconds earlier to stop them? And then the villains go back a generation earlier and try to kill the parents of the PCs? And the PCs follow them? If time travel/manipulation is a force in the game world, why hasn't some BBEG gone back to the dawn of time and stopped humans from ever evolving? Why hasn't a future villain come back to kill the PCs when they are 1st level? Why doesn't being saved by your future self put you into a time-loop?

I've explained that creating a paradox would force the player characters to have to remove that paradox. The same applies to the bad guys (if indeed there are bad guys with the power to manipulate time as well). Thus, these problems, when they crop up, would have to be resolved. I've made a number of references to "a magic item that comes up twice" which is the simplest form of paradox. Most others are variants of this. If you create a loop, you have to correct it. However, "if the loop never exists, then how would you correct it" will have to be thrown out.

Perhaps a rule of thumb that you can never "stack" paradoxes? That would probably be fairly requisite to prevent the problem of "ok, you fixed it, but now you have to fix it so that you go back and fix item" problems. Yes... I think that should be one rule of thumb.

I'm not trying to annoy, but you're opening a huge can of worms. It's a good, tasty, exciting, head-spinning can of worms...and fun too! But my advice is to try to know the answers to as many questions as you can before the game starts, and set some ground rules.

I like my worms, damnit!

 

[Creamsteak]

This might be a good thing to read: http://en.wikipedia.org/wiki/Time_travel. It outlines many different ways fiction has dealt with time travel. I especially like 1.2 or 2.1 universes (scroll down the wikipedia entry to see what I mean).

Very cool. Thanks, gave me something to read through computer-science class.

You could drive the PCs nuts forcing their future-selves to fulfill past-self requests. Don't the future-selves have better things to do than travel back in time and kill kobolds for the past-selves? Conflicting priorities would be fun to play with: "We have to kill the beholder that threatens to destroy the kingdom but we REALLY have to go back in time to make sure we survive the orc invasion 10 years ago! If we don't, we will cease to exist!"

Well... I don't want to drive them "nuts" about it. But I think it could be very cool if done right.

Another way of introducing time travel would be to do it at a smaller scale. Use the video game concept of saved games. Give each PC a limited number of Time Orbs that, when crushed, erase the last x hours/minutes/rounds. This could be really fun in a combat: Crush a time orb to "do over" the last 1d4 rounds. Use one on round 6 to undo the savage coup de grace suffered by the held fighter--but wait--now we have to redo round 4 when the wizard got lucky on his fireball and rolled high damage!

Hum... well that's a totally seperate idea... but it could be interesting.

Here's another idea: the future-PCs have returned to stop, by all means necessary, the present-PCs from making a dire mistake. Don't reveal the identity of the enemies until it's almost too late ("Crap! I disintegrated myself!")

Heh... yes, I'm thinking that at least a few times they need to encounter "alternate us's". Perhaps even encorporate the "evil us's" from another timeline into it at some point.

Play the campaign backwards. Start the PCs at 15th level and work back through time and levels.

Ooh... that could be very neat too... but it would be hard to handle unless everything in the backgrounds was worked out very well before hand. Perhaps an adventure late into a campaign could handle this.

Man, now I want to play a time travel campaign!

Your not the only one, I think.

 

[Creamsteak]

The only way this could work with a villain is if the villain time travels too. He can make sure his identity remains hidden, and he can undo events that would ruin his plans.

Not necessarily. I can think of a handful of other options. An immortal or godlike entity could still present a challenge. Also, a long-standing religion or cult could create serious problems. Also, perhaps it is inherent in the campaign (such as "Oh . The wizard in our party is the real bad guy, only 6000 years in the future when he's a super-evil lich lord of half the multiverse." or the more popular "evil us's.")

You could use an approach from the video game Chrono Trigger. Time streams run parallel, and there are distinct eras that don't overlap. What constitutes a time stream varies for each traveler, but if I were to use my campaign, it might look like this:

Feh... never liked that approach myself. Felt too much like a way of trying to create an arbitrarily simple excuse to do cool things.

One key thing here, though, is that some things can exist independently of time. If a creature is truly immortal, it can travel back in time to become its earlier self. Matter traveling through time is not the issue, since everything balances out in the end. What is the problem is information.

*SNIPPED*

And of course, the climax of the campaign is dependent upon a character willingly letting himself be undone so he can save everyone else.

Those two ideas seem really cool too. Hrm... so many ideas.