Watch Out For These Time Travel GM Traps

Movies and books make time travel stories seem easy. We watch with excitement as characters tackle crazy time paradoxes and puzzles, battle villains in a variety of lush settings, and experience fun twists made possible when authors can play with timelines.

The scam for us poor game masters, however, is we are more prone to railroading with time travel plots. Also, our time bending ideas cause our plots to become rigid and brittle, which make our games likelier to break once players get involved.

Most game genres offer the potential for time travel. Fantasy has magic, be it powerful spells, mysterious artefacts, or one-time wondrous events. Modern day and science fiction settings offer secret technology, alien technology or powers, or supernatural events.

RPT reader Robert M. emailed me recently to ask for tips on time travel:

  • What are the traps and pitfalls to avoid when running time travel?
  • What are some of the great moments to run in time travel?
  • Where can I find out more?

Thanks for the tip request, Robert. Here are some GM tips to consider.

For mission-style, run it just like a dungeon

I lump time travel campaigns into two groups: sandbox and dungeon.

Sandbox means the players can travel to different times, worlds, or even dimensions of their choosing. The whole galaxy (and more) is open to them to poke around in. The PCs might have quests and objectives, but they have the controls to go where they want. Think Dr. Who.

Dungeon style creates linear games. Locations and foes are all constrained by the dungeon map. PCs explore the map, following routes allowed by exits, entrances, and connectors between locations.

The difference between the two styles for time travel is the game master’s pain threshold.

I kid, I kid. However, be warned that if you give the PCs control over time and space, they can go anywhere and anywhen. You will need to make up people and places galore. Are you up for that?

I prefer to run mission-style adventures that you can plan just like a dungeon. Think Stargate.

Locations, events, and NPCs are tied to predictable plot progression. Use standard dungeon design techniques to offer the illusion of choice.

For example, you might choose the nine act format. Each act requires specific things before it can start and end, giving you planning and design control. However:

  • Within each act, you design several encounters players can trigger in whatever order they choose
  • Players can also ignore or bypass certain encounters
  • Players can trigger unplanned encounters that you make up on the fly
  • Characters go where they want, do what they want
  • But until the act advancement conditions are met, characters stay within an act

Think of each act as a bubble. PCs can bounce around inside each bubble however they want, but they remain in each bubble until they advance the plot, as per your design. Half railroad, half dirt track.

Doing time travel dungeon-style lets you plan some things in advance, keeping your sanity as GM. More advice follows on how to do this in the Set time travel parameters tip below.

Know your timeline

In other campaigns, players will ask, “So tell us about the world.” However, in time travel campaigns, players will ask, “So tell us about history.”

Have a timeline prepared. You can keep it rough, to prevent over-planning and over-detailing. A bullet list with dates is great:

0 IC – First alien settlement

1,500 IC – Second aliens arrive on planet and settle

2,000 IC – Alien war breaks out, first aliens win and enslave second aliens

3,500 IC – Empire formed

5,300 IC – Empire breaks apart, world gels into numerous smaller states

7,800 IC – Holy leader emerges, unifies half the world, creates peace between two alien races

Present Day – cracks emerge in holy empire, racial tensions renewed, conspiracies everywhere between factions who want to save the empire and factions who want it to end

There are countless notable events within that 8,000+ year timeline, which we’ve condensed into just seven points. However, if you were GMing this world, wouldn’t having this give you some peace of mind? A bit of confidence when planning? Some structure to help form your ideas around? It does for me.

I would aim for more bullet points for key adventure locations. Earth in Dr. Who, for example, gets visited often.

If your let the PCs travel to any world, any time, then you should create a larger timeline for the entire area the PCs can travel to. If the characters can go between dimensions, visit alternate timelines, or even go to places outside of normal space, you should have a basic timeline for this whole combined region.

Then splinter off separate timelines for key worlds or areas.

That gives us a big picture of the past and present. What about the future?

The answer depends on the rules of time…

Create your rules for time

As of 2011, we do not yet know how time works. We have ideas, theories, and some growing knowledge, but it’s still all up for grabs. Therefore, any decisions you make about time travel will be fiction. You do not have a body of definitive science and answers with which to create consistent time travel game rules. So, you will need to make your own.

Not having the rules of time laid out in advance could end your campaign early (dare I say, before its time?). As PCs take their actions, various paradoxes and issues will come up. If you do not give them careful thought in advance, then your ad hoc rulings will eventually create a knot so tricky that you cannot smooth things out. The campaign ends as nobody has traction on game reality any longer. You might as well roll on a table to see what happens next.

Key time issues to resolve for yourself

  • Why is time travel not present, known, or revealed in history?
  • Can you change the present by going backwards in time and causing a difference?
  • Is there one timeline or time stream, or more? Explain.
  • Can someone from the present or future send messages to someone in the past?
  • What happens if someone kills a PC in the past? What happens if PCs meet themselves?

Another key issue is opposition. If there are time travelling villains in your campaign, then why have they not struck first, preventing any interference by the PCs or others?

Set time travel parameters

Put limitations on PCs’ time travel so you steer and pace things better to avoid becoming overwhelmed.

If the full can of worms is open in your campaign, then not only can characters travel to different times, but they can visit unlimited worlds plus the various times in those worlds! If that does not make your head explode, then realize it means the party can also hop genres. Historical, steampunk, modern, cyberpunk, sci-fi. If the laws of your universe allow it, you might even have magic on your hands in the form of spells, supernatural, psionics, magic items, or gods.

All in one campaign! And all at the PCs’ beck and call? Yikes.

If this is your first time travel game, put numerous limitations on time travel so you can keep the game manageable. This also helps the players, for if they have unlimited choices, then they could feel caught in the blinding headlights of a temporal semi-truck.

Use a home base

Avoid giving the PCs a time travel device. Instead, design a home base with time travel capability, such as Stargate has done.

This limits the amount of hopping PCs can do. Depending on how you design the return mechanism (how can the PCs return back to the home base each time?) you create at least one stable game element.

You can also put temporary or permanent restrictions on the home base time travel mechanism, such as:

  • Cool down period – PCs must wait before travelling to another time, or possibly returning to home base after each trip
  • Fixed number of destinations – only certain worlds, time streams, or dimensions are available
  • Timeline blackout periods – parts of the timeline are unreachable
  • Charges – a neat way to put an end state in the campaign, unless you opt for quests to recharge the mechanism
  • Fuel – require a rare element or fuel source that gets consumed each time travel trip

A clever limitation is creating blackout periods on times the PCs have already visited. This prevents several time logic problems, and prevents abuse of the ability so the campaign does not turn into a Groundhog Day game.

How much matter can travel?

How much can be transported through time – six people, entire armies, or somewhere in between? How much equipment can the characters take with them through time?

This decision gives you key control over the resources and options players have so you can achieve the kind of game balance you want.

For example, if you allow 2,000 pounds maximum to pass through time, that prevents the PCs from hauling tanks, spaceships, and wads of gold with them.

However, in this case, have an answer for potential player attempts to game the system. For example, why can’t they make multiple trips, bringing their spaceship through time in pieces?  (The cool down and timeline blackout options are good answers.)

How can history be manipulated?

If you can prevent the villain from being born, can the PCs win the game in the first encounter?

Be careful about how history can change. Be sure to have your rules for historical interaction ruled out.

Even if you run a fantasy setting, where history need not mesh with any kind of Earth reality, the question of abuse still needs an answer so your campaign does not short-circuit by accident.

Remember the TV show Sliders? That show offered dimension travel rather than time travel. You might decide to create one rigid timeline, where history cannot be changed, and if the characters do go back in time and meddle then that just creates splinter timelines. That offers you an easy out on many time paradox issues.

I also favour a blended approach where you give the official time line a strength rating. Any events that change history that do not meet or beat this strength rating mean splinter timelines spawn.

If an event is so powerful or important that it does exceed the official timeline’s strength rating, then official history does indeed change.

Only dramatic situations will cause changes to the PCs’ timeline, which offers great fodder for villains and adventures.

Decide how history works in your game before the players opt to change it.

Create a list of culture seeds

With many potential cultures just a short trip away, you will be pressed to come up with distinct ideas, else risk different locations blending together into a vanilla lump.

Have a list of culture ideas ready. Dig into Wikipedia for inspiration. Research countries, cities, and civilizations. Create a list of at least 12 culture ideas, preferably twice that number.

For each culture seed or idea, use the elevator pitch or X Meets Y format.

An elevator pitch gives you a short period of time to make the sale. In RPG terms, this means writing a paragraph or less that describes why a culture is unique and fun to game. The pitch should be interesting enough to immediately hook players.

The X Meets Y format mashes two ideas together so that you instantly understand the potential and uniqueness of the idea. X is typically a culture reference from real life or fiction. Y is some other idea, possibly a culture, but probably something else like a technology or condition. Then you mash X and Y together to form your culture.

For example, the Gem Society. Roman Empire meets different types of gems (and gem qualities).

Because you are familiar with X and Y, you can describe a cool concept in few words, which means faster preparation!

Create culture clashes

You should also think about creating a conflict within each culture. The PCs will not visit the entire culture. They will just drop into a small number of locations to explore or complete an objective. So, your conflicts should be a combination of environmental and personal to add an extra dimension to each setting.

For example, the group is sent to an asteroid mine to take pictures of alien drawings discovered hundreds of years ago before they were destroyed by careless miners. This is part of a larger plot, and the villain has placed agents at the mine throughout that time period to block any enemies from observing the drawings.

You decide the culture for the mine is Prison meets Rasputin. The prisoners are being led to revolt by a powerful guru.

Such an environment makes the whole encounter or adventure more interesting, adding a new dimension to the standard villain vs. PCs plot.

Time travel resources

Mike Bourke at offers extensive advice on the subject in his excellent three-part series, Time Travel in RPGs.

You might also want to check out GURPS Time Travel.

More time travel tips, please

What about you? What advice do you have for Robert?

  • What are the traps and pitfalls to avoid when running time travel?
  • What are some of the great moments to run in time travel?
  • What are some great time travel resources?
Sean Holland

My general advice on time travel is . . . do not do it. It is just so messy.

But if you are going to use it, read some of the stories on time travel. I recommend Poul Anderson’s Time Patrol, H. Beam Piper’s Paratime, and Fritz Leiber’s Change War series. This will help to give you the tools to decide how you want time travel to work in your game.


I remember the old Blackmoor modules from DnD basic had time travel. The jump into the past was so distant the players had very little chance to affect the present. The players were also limited by location and time. Imposing a set period to complete a mission tends to focus their attention.


In my mind, a time traveller would just be a splinter in a wound. Time (the wound) will heal and eject the anomaly (the splinter) over time. You can thus only disturb local and contemporary spacetime. This theory might help tp avoid plot holes, just tell the players that time has healed.

Zak GM

I only allowed my players to go forward in time. First through magic in the Dark Ages shortly before the fall of Constantinople and then via SCIENCE for the consecutive ones up through the present/close future 2021. The last time they “jumped” was via help from a scientist they encountered and assisted rebuilding his ship only after convincing Nikola Tesla to help. They caused a few minor “rifts” in the timeline, but most important the loss of the “Spear of Destiny” effected many historical aspects in MY game. WW1 never really ended until the 1950s due to the players bumbling in the 1890s and Hitler then never came to power. We are now somewhat post-apocalyptic w/ Yosemite blowing it’s top! They will inevitably get caught in the 1st worm-hole test (that created their 1st taste of science from the scientist in the 1890s); @ area 51 and then catapulted into the distant future w/ aliens and space colonies etc. This has been planned since the very beginning of the campaign 2 yrs ago.
Only suggestion, plan ahead! Think about the most important things in your world, what can change them and what can fix them! I only went FORWARD in time… if I allowed them to bounce around, plot would have been extremely difficult in my game. They also had to adjust to their time and learn common ENGLISH, driving, what GUNS were and cars etc.! It’s a fun roleplaying experience for your player trying to figure out what PIZZA is! :) Over all… give it a shot, maybe limit the timespan to start out w/ until they can unlock a code or soemthing to go further. Good luck!


The whole time travel thing should not be a problem for experienced GMS. It is no different than letting players go to other worlds or planes of existence. My simple rule for PCs effecting the past is this: They can’t. If they go back in time and kill Hitler as a child, some other person with the same name takes his place. So while they change think this has a lasting impact it doesn’t. Put simply, you can’t change time. traveling to the future is even simpler, it has been created yet so you can make it anything you want and change it as needed. This is all fantasy after all and only a small amount of consistency is needed to keep it “realistic”. I have one campaign where the PCs can go anywhere and do anything they want. I find it challenging and stimulating to come up with people, cultures and civs on the fly. Just like the old module Queen of the Demonweb Pits where on level 4 there are gateways to other dimensions and planes. Only a brief papragraph was given and the GM had to make everything else up on the fly. This is the best way to GM in my opinion, none of my campaigns or adventures are written out ahead of time(except for maybe a map), they evolve thru my own creativity and the actions of the PCs. So in my opinion time travel or dim travel is not difficult at all. Just like anything else in your game if you let it get out of hand, the players will run with it and make you wish you had kept that door closed.

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