Marcus L. Rowland (ffutures) wrote,
Marcus L. Rowland

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Time travel thingy design notes

Still ill, but I've trying to get some writing done anyway.

Here's the design notes and acknowledgements for the time travel thingy. Let me know if you think they're over-long or there's anything that needs to be added (especially your name if I've missed it). A few of the links below won't work since they're to some of the other files in the next release of the game, the rest ought to.

Design Notes

During play-testing several people asked me why I'd chosen this particular form of time travel, and limited it to big ships. There's no simple answer, but very briefly...

I don't honestly believe in time travel, but I think that if it was possible at all it would be possible to change the past, either by replacing the previously existing turn of events or by splitting the time line. Hawking and others suggest that time line splits happen continuously, at everything from the quantum level upwards, billions of times a second. While it's difficult to imagine a universe that works that way the evidence and theory appear to be reasonably good, more convincing than for a single time line.

The same theories suggest that it won't be possible to travel between time lines, and I've had to fudge that a little in sending time travellers back along their existing time lines, as well as to the new ones. If that didn't happen the time machine would be an unknown quantity; switch it on and you disappear, never to return. It's unlikely that many would be built, or that many people would be stupid enough to try them.

This idea has another big advantage for game designers, referees, and players; since you're never in the same time line twice you don't have to worry about elaborate rules for avoiding time paradoxes, keeping track of fights that move back and forward in time, and some of the other complications that plague time travel RPGs and sometimes seem to make them look like a book-keeping exercise. While it's just about possible to help your original past self (but you still need a ship and crew, transport from the coast to wherever you're in trouble, etc.), there is no way for two separate instances of the same time traveller to interact. You can't create an instant army by travelling back to the past again and again; you can do it by bringing the same person to the present again and again, using the "Sorcerers' Apprentice" trick, but there will always be time lines where it doesn't work, they are separate people (and will not regard themselves as expendable) and they can never go home again.

Restricting travel to the past (of the time machine, though players may initially think that there is an absolute ban on travel past their own time) is another way to keep the game controllable. Adventurers can't easily go past their own time to get ridiculously powerful weapons and other cool stuff from the future. Incidentally, does anyone really think that a futuristic government is going to let primitives from the past buy amazingly powerful weapons? No, me neither...

Another common problem is the use of time machines to bypass defences. In many games it's possible to travel back to before a fortress or a bank vault was built or forward to a time after it was destroyed, move your time machine there, then move through time and materialise inside the defences. Characters can easily bypass bodyguards, vault walls, etc., which makes it more difficult to give them a challenging situation. Use of ships which have to physically manoeuvre to their destination avoids this problem completely, and will usually leave characters with the additional problem of getting ashore, locating transport, dealing with the natives, etc. It gives them more to do, and ensures that they'll have to interact with the local situation. Hopefully they'll end up seeing the natives as people, not targets.

MPH (kt)
1 hr
24 hr
Running0.110 (8.7)2.47-530 min226 dy*
Bicycle0.115 (13)2.47-51.2 hr2 y*
Horse & rider0.715 (13).000179.1 hr14.4 yTrot *
Horse & rider0.735 (30).000174.6 dy176.6 yGallop *
Model T Ford0.5445 (39).000137.9 dy299.4 y**
De Lorean1.23110 (96).00030269 dy4290 y**
Titanic46,32928 (24)11.44433 y5.99 MY
USS Nimitz102,00035 (30)25.191861 y25.74 MY
Broadsword18.686 (74).004645.15 y71193 y**
Rapier15.0120 (104).0037011.4 y157681 y**
Claymore29.075 (65).007165.38 y74426 y**
*These speeds are not sustainable
**Top speeds, cruising speed is lower
(24-hour range exceeds normal fuel capacity)
The lower mass limit on ships is there for the same reason; it's high enough that it's extremely difficult to build useful time machines that aren't big ships. The spreadsheet templates don't incorporate the limit, so if you want to build time machines that ignore it go right ahead. The table to the right gives a few vehicle examples to help you, plus a couple of famous ships from later eras. All of these examples assume that the Temporal Displacer has negligible weight and power requirements; if you are using a vehicle design system, as in The Queen's Own Aerial Hussars, you may want to change that.

There are no upper limits on mass stated, apart from a cost per thousand tons and an assumption that it's contained inside a metal hull. An early draft of the background involved an experiment which accidentally moved the entire planet Earth several thousand years through time; unfortunately the Moon and Sun didn't go with it, and by the time the Earth got back to the right time it was well out of orbit and on a collision course with the moon, now orbiting the sun as a small planet. If you want to give players the power to destroy worlds you can leave this idea in, but I don't really recommend it and I'm not going to do the maths for you...

Another reason for limiting the method to ships is that a vessel with several hundred people aboard can generate endless plots of its own; even a freighter will need a lot more crew than the average group of adventurers, so there can be plenty of NPCs with plans of their own, or an uncanny ability to accidentally mess up the adventurers schemes. An ocean liner is almost a floating town; it can survive on its own resources for several weeks, much longer if food and fuel can be obtained locally, and will carry a doctor and nurse with a fully-equipped surgery, mechanics and workshops, members of any reasonably plausible profession, and endless people with potentially useful knowledge. If you're going to get lost in alternate time-lines or marooned in the distant past they're going to be needed. The metal and other materials in the hull can also be very useful in this type of situation. It may also be worth mentioning that a liner probably contains enough people of child-bearing age to repopulate the world without in-breeding problems, which may be very helpful if it's wrecked in the deep past or an alternate time-line without people.

My final reason for writing it this way is that I think it's fun, which is something that occasionally gets overlooked in justifying how RPGs work. I love the idea of Queen Elizabeth I negotiating with the officers of a time liner, the Corinthic cruising past a school of plesiosaurs, the sky over the ocean lighting up as an asteroid plunges into the Gulf of Mexico half a world way, staid Edwardian naturalists wrestling with a moa, giggling Victorian schoolgirls meeting Da Vinci and Michaelangelo. I think it works, and I think it's fun. I hope that you'll agree.

Sources and Acknowledgements

Special thanks to Simon Bradshaw, Peter Cohen, Paul Cray, Mavis Cruet, Paul Drye, Sir Ernest, Matt Goodman, Chris Holliday, Don Sample, Charles Stross and many others for their encouragement, help and feedback while I was developing this section.

  • Period sources
  • Modern Sources

    • Poul Anderson: The Corridors of Time (and many other time travel stories)
    • Stephen Baxter: The Time Ships (authorised sequel to The Time Machine)
    • John Brunner: Times Without Number
    • L. Sprague De Camp: A Gun for Dinosaur (anthologised in Rivers of Time with other stories about the same characters), Lest Darkness Fall
    • Eric Flint: 1632, 1633
    • Harry Harrison: The Technicolor Time Machine
    • Stephen Hawking: A Brief History of Time
    • John Kessel: Corrupting Dr. Nice
    • Richard Meredith: The "Timeliner" trilogy
    • Alan Moore: Time Twisters (collected comics)
    • Larry Niven: One Way Street (short story, various anthologies)
    • S. M. Stirling: Island in the Sea of Time and sequels
    • Twelve Monkeys (film)
    • Michael Swanwick: Bones of the Earth
    • Seven Days (TV series)
    • The Terminator film series

  • RPGs

    • FASA: The Doctor Who Role Playing Game (out of print)
    • Pacesetter Games: Timemaster (out of print)
    • Steve Jackson Games: GURPS Time Travel (much of the same material is in the forthcoming GURPS Infinite Worlds), GURPS Timelines (to be reprinted 2006), GURPS Dinosaurs, and several sourcebooks e.g. GURPS Rome, GURPS Greece, etc.
    • Virgin Games: Timelord (Dr. Who RPG - Out of print)

  • Web sites


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