This article originally appeared in Pyramid #21

23 Skiddoo

Designer's Notes and an Alternate Campaign Frame for GURPS Alternate Earths

by Kenneth Hite, Craig Neumeier and Michael S. Schiffer

The time is out of joint: o cursed spite, That ever I was born to set it right! Hamlet, Act 1 Scene V; unofficial motto of the TIA

GURPS Alternate Earths is designed as a supplement for the "Infinite Worlds" campaign frame in GURPS Time Travel. It provides six new worlds for the Infinity Patrol to adventure in, keeping the continuum safe for Homeline tourists and Infinity Unlimited's investment portfolio. However, it originated in a somewhat different campaign predating the publication of GURPS Time Travel by several years. "23 Skiddoo" is that campaign frame, retrofitted for GURPS Alternate Earths GMs who want the faster pace and adrenaline rush that only multidimensional Time War and rapid-fire history-changing can provide.

Anthony Leighton and the TIA

During the darkest days of the Cold War, Anthony Leighton was working at the Ronald Reagan Superconducting Supercollider in Waxahachie, TX. His specialty, high-energy field physics, was critical to America's quest for a missile defense against Soviet ICBMs. Ligachev had overthrown Gorbachev in a coup in 1990, and the USSR was moving to restore its empire in Eastern Europe. Fighting broke out in Poland and Germany, exploding into World War III in 1991 as the Red Army crushed dissent in Eastern Europe and moved against NATO. The winter of 1992 saw a limited nuclear exchange, but when the smoke cleared, the Soviet system collapsed the strains of war were too much for it. The former Soviet satellites became independent, the Soviet Union was dissolved, and America was able to turn its massive engineering might into peacetime pursuits. Along with warm-temperature superconductors, microwave-power satellites and other benefits of advanced research came Leighton's discovery of time travel.

Announced in 1999, time travel had actually been developed almost a decade earlier, and a top-secret CIA "Project Flashback" had run through several iterations of World War III until an American victory had been secured. This truth, that time not only could be changed, but had been changed repeatedly already, was kept from the world and the cover story of Leighton's discovery was promoted with massive fanfare. The U.S. formed the Temporal Intelligence Agency (TIA) under U.N. charter, offering jobs as researchers, policemen and historians to citizens of any nation (who passed the strict background checks.) The TIA headquarters was established at Waxahachie and the TIA began patrolling the timelines. Keeping saboteurs, cranks and thieves out of the delicate past while allowing historians, scientists and other scholars to study history first-hand kept the TIA busy for six years. "Portable" time machines, the size of a small minivan, made researching the past easy while increasing the danger of unauthorized intrusions.

The Reality Wars Begin

In 2005, a freak accident at the Waxahachie projector led to the discovery of "sideslipping," travel into parallel Realities. "Reality Beta," the world the TIA entered, was ruled by a Rome that had seemingly never fallen. Unfortunately, the TIA agents discovered that at least one other Reality had already mastered "sideslipping" a Nazi-dominated world that the TIA dubbed "Reality Gamma." Reality Gamma was already working to destabilize Reality Beta when the TIA intervened, leading to a crash program of exploring the worlds on the other side of the sideslip.

The rivalry between the TIA in Reality Alpha and the Zeit-SS in Gamma soon flared into open conflict. However, both sides soon realized that they had another enemy to deal with, "Reality Zeta." This mysterious timeline, where apparently Ming dynasty China had conquered the world, used a means of psionic reality travel unlike that of Alpha or Gamma.

As the campaign begins, these three intertemporal superpowers fight a war of influence across a backdrop of multiple timelines all branching off from an original reality, which began splitting for some unknown reason at the time of the dinosaurs. In fact, there are 23 realities, although the TIA begins with knowledge of only six. (Gamma knows about one or two others, Zeta may know of them all.) Although the local present differs between the realities (Alpha is in 2006; Beta is in 1878), all advance at the same rate.

Time Travel Mechanics

Time travel within individual lines is simple provided you have the proper equipment. A Leighton Effect device is too large for an individual to carry, but may be mounted in any vehicle. When it appears in the past, it emits a radioactive gold-198 signature (travel into the past produces gold-198 as a byproduct of a tachyon reaction). Reality Alpha and Gamma have monitor satellites in critical eras of their past that detect unauthorized incursions and warn the future about them with remote drones.

Time machines in the past cannot jump farther back, or return only partway to the present; a conservation law forces return to the true local present of the timeline. Linearity is normally conserved; a time machine spending an hour in the past must return to the future an hour after it left. Probably as a related effect, no one can meet themselves in the past or at least everyone who has made the attempt has failed to return.

Time is plastic with high resistance; history can be changed only with difficulty. Small changes dampen out; large changes, however, cause the timeline to "jump tracks," often altering history radically. Possibly as a side effect, a "successful" alteration to the timeline breaks linearity, causing the traveler to return at least several months later than would be expected. Time travelers pastward of the change notice nothing until they return to the altered present; time travelers futureward of a change apparently blink out of existence with the rest of the world.


Sideslipping is a more limited application of the Leighton Effect than time travel. Only organic matter can make the shift into another dimension. Alpha and Gamma use large projectors that send agents across realities but do not move themselves. These projectors can only function in local present.

Returning, then, is a problem. Alpha has devised a "homing beacon" which can link to a projector on Alpha, enabling retrieval. The beacon requires metal components, including gold, and therefore must be constructed by travelers using local resources. Ideally powered by direct current, a beacon may be modified to function when struck by a bolt of lightning.

Reality Zeta travelers can (and do) use ordinary Leighton time machines, but they also use a psionic method of reality travel that is not understood by Alpha or Gamma. This power, however, allows them to transfer agents from the past of one reality to the past of another. Note that Zetan agents sideslipping into the past cannot be detected by gold-198 emissions.


TIA agents engage in three basic kinds of operations: exploration, damage control, and chronotage. Exploration missions can either be to some ill-understood event in the past or to a newly-discovered parallel world. In the second case, agents will need to acquire sufficient information about the new world to make the trip worthwhile, and build a beacon in order to return. A group sent into a non-technological parallel will find this challenging.

Missions into the past can become damage control, if the group returns to the "present" to find everything changed. The group must examine the new alternate history in order to determine the change point, return to it and restore the original course of time. Fortunately, the monitor satellites often give warning of unauthorized intrusions, allowing the TIA to send preemptive response teams to stop the intruder before history can be changed. (Linearity is conserved; rapid response will give the intruder very little time to effect an alteration.) Chronotage missions send agents into another reality with instructions to find a time machine (often secreted by agents in place) and attack its past. Damage control teams will certainly be dispatched to block the agents, and history is difficult to change even without active opposition. Of course, Gamma's ZSS mounts its own chronotage operations against Alpha and its allied timelines.

The 23 Worlds

Alpha: "Homeline," base reality of the TIA. Local present 2006.

Beta: Roma Aeterna, from GURPS Alternate Earths. Dominated by a TL5 Roman Empire, allied with Alpha and the TIA. Local present 1878.

Gamma: Reich-5, from GURPS Alternate Earths. Nazi-dominated reality, TL8 with time travel and sideslipping. Local present 1994.

Delta: TL6 reality splitting at the Glorious Revolution of 1688. Republican revolutions are in the process of destroying the hold of Bourbon France and its Hapsburg allies on Europe. Alpha supports the Republicans. Local present 1943.

Epsilon: Islamic-dominated reality diverging during the early caliphate. TL9 but without time travel (the scientific revolution occurred in the 10th century), has colonized several other star systems. Neither Alpha nor Gamma want to risk attracting the attention of the Rightly-Guided Stellar Caliphate. Local present 1684.

Zeta: Chinese-dominated reality, diverging with the Ming sea voyages of the 15th century. TL of this world is unknown; their agents use only local technology. Unlike any other timeline, Zeta has developed psionics. Local present 2000?

Eta: Post-disaster timeline which reached TL9 or 10 before collapsing about 100 years ago. Apparently diverged with Alexander the Great; his successors built the space stations and other artifacts still dotting this mostly empty world. Local present 2055.

Theta: Dixie, from GURPS Alternate Earths. The CSA won the Civil War, and is currently locked in a Cold War and space race with the Union. TL7, local present 1984.

Iota: A Christian Mongol Khanate, converted by a more successful Marco Polo mission, rules most of Eurasia but is being wracked by the Reformation. TL4, local present 1612.

Kappa: Dinosaurs, millions of years after they should have died out. Returning from this reality will require psionics or building a technology up from TL0.

Lambda: Ezcalli, from GURPS Alternate Earths. The Aztecs are the leading power in this TL5 reality, contesting with the Iroquois and the empire of Songhay for the spoils of the Mongol Khaganate. Local present 1840.

Mu: Apparently destroyed in a global nuclear holocaust a few years ago. The fabric of reality is weaker here, and people and things can sideslip in or out without warning. Local present 1993.

Nu: Gernsback, from GURPS Alternate Earths. The World Science Council benevolently rules a world transformed by the inventions of Nikola Tesla. TL variable (6-13), local present 1965.

Xi: The Spanish Armada succeeded in 1588, and the Spanish Hapsburgs rule a global empire opposed by bands of pirates in the Caribbean and Indian Ocean. Reality Gamma has so far used this timeline only as a source of treasure. TL4, local present 1715.

Omicron: Society is based loosely on Icelandic semi-anarchy; the nation-state collapsed as an institution centuries ago. Original change point unclear due to unreliable records. TL7, local present 1970.

Pi: Explorers from Gamma and Zeta have failed to return from this timeline.

Rho: Victorian British Empire presides over the world. Diverged with reforms of 1763 giving American colonies a voice in Parliament. TL5-6, local present 1894.

Sigma: Cretan matriarchy one of few civilized areas in TL1 world. Local present is so early (1800 BC?) that no one is quite sure how its history differs from Alpha's.

Tau: 1908 meteorite destroyed St. Petersburg instead of Tunguska, plunging Russia into anarchy. Gamma is aiding Kaiserine Germany's attempt to fill the power vacuum. TL6, local present 1923.

Upsilon: Complex political balance of Celtic overseas colonies, Teutonic-dominated Egypt and Khazar Empire. History shows signs of tampering by time travelers. TL6, local present 1932.

Phi: American revolution crushed in 1778. Stagnant European monarchies challenged by revolutionary democrats in Russia. TL6, local present 1981.

Chi: Shikaku-mon, from GURPS Alternate Earths. Quadripolar balance between France, Brazil, totalitarian Swedish Empire and Catholic Japan. TL8, local present 2015.

Psi: Diverged with Turkish invasion of Italy in 1480s. Ottoman Empire dominates most of Europe and the world. TL5, local present 1876.



The PCs in a 23-Skiddoo campaign should be TIA agents built on 150 points. Although most TIA agents are from Reality Alpha, the GM may allow PCs to come from a parallel world, especially as the campaign progresses.

Considering the limited technology that can be transferred between worlds, the GM may allow genetic engineering of advantages such as Absolute Timing, Absolute Direction, Acute senses, Combat Reflexes, High Pain Threshold, Lightning Calculator, Night Vision, Rapid Healing and Toughness. Psionics are available with an Unusual Background and GM approval.

Cliology is an optional specialization of the History skill; it allows the character to predict the effects of a historical change, or work backwards to locate the change point that created an unknown present.

Notes for the GM

Exploration and damage control missions allow (and the latter almost require) substantial control over the course of events. Chronotage missions, however, allow the ingenuity of the PCs free rein, especially if successful. If the GM is not able to improvise altered histories on the fly, the players' changing history should coincide with the end of the play session. This at least gives the GM some time to work out the effects of a successful act of chronotage.

Because the setting of the campaign is so variable, a sense of continuity depends largely on NPCs. Colorful running villains, helpful Alphan researchers and perhaps the PCs' superior officer can recur through many adventures, even if history is changing around them.

Article publication date: September 1, 1996

Copyright © 1996 by Steve Jackson Games. All rights reserved. Pyramid subscribers are permitted to read this article online, or download it and print out a single hardcopy for personal use. Copying this text to any other online system or BBS, or making more than one hardcopy, is strictly prohibited. So please don't. And if you encounter copies of this article elsewhere on the web, please report it to