Character generation in this period is much like it is in the Weird West or the Wasted West, except that, due to historical concerns, certain Arcane Backgrounds are treated differently.
Things were pretty wild back in the Weird West. The Battle of Gettysburg was only the first of many battles in which the dead rose and fought everyone, whether Grey or Blue. The bloodshed was multiplied several times over, and it's a wonder that anything was left of the Americas, even split into the North, South, and the Sioux Nations. Eventually, though, it died down. Maybe the heroes of the Weird West were supposed to have defeated the Manitous around the turn of the century, but the Reckoners "cheated" and sent back Stone to kill them off, and now Earth is headed toward the horrors of the Last War.
Or, maybe that's just a bunch of hogwash, invented by people who just couldn't accept that the good guys don't always win.
Whatever the case, the supernatural is still alive and well in the early 20th century. There's a great deal more bloodshed going on, in the form of World War I, and then World War II, and all manner of atrocities, such as the Holocaust, with deaths measured in the millions. That said, Gettysburg is not being repeated. The dead are not rising in armies to overwhelm the living. The Reckoners are quietly biding their time, waiting for the right moment, though they're still planting seeds of fear. But with such real-life horrors as the "Final Solution" ... who needs monsters?
The forces of good are likewise keeping it low-key. Heroes with arcane powers are the exception, not the rule. Newfound belief in science -- true science -- has caused new "recruits" to their number to dwindle. And those few who flaunt their powers are relentlessly hunted down -- not only by individuals such as Stone, but by world powers anxious to claim any trace of the supernatural or the extraordinary for their own uses. A Mad Scientist who shows off his rocket pack in a grand demonstration to the masses may soon get a "deal he can't refuse" from the government -- whether his government, or another. A Syker might end up on a vivisection table. A Witch might not get burned at the stake, but if she isn't careful, lynch mobs are still around.
The rule of the game here for characters with Arcane Backgrounds is to be subtle. This isn't a time for hex-slinging duels on Main Street at high noon -- not that it ever was, even back in the Weird West. Anyone who makes use of his powers publicly is going to need a secret identity ... or a good life insurance policy for his loved ones. Hucksters still pass themselves off as gamblers or stage magicians. Martial Artists can get by with a few amazing feats, passing them off as "well-conditioned reflexes". The Blessed tend to have powers that are undetectable in everyday life (such as "Protection"). Mad Scientists may be few and far between, but at least they can pass off their inventions as "science".
There are people who openly claim to have powers of the occult. It's a common schtick of stage magicians, and there are plenty of spiritualists (with or without actual powers) who claim to be able to speak with the dead. Still, most people can rationalize this away as mere showmanship, or simply don't see this as something that affects their everyday existence.
Players bringing Witches that fling glowing green human skulls around, however, are going to be soon writing up a new heroine.
The Weird West is in the past. The manitous that were whispering in the ears of wild-eyed inventors are still around, but in fewer numbers -- a trend that will continue, right up to the point of the invention of the Ghost Rock Bomb, off in the future. Sure, rocket packs existed in the Weird West, as demonstrated by the Flying Buffalos, and Smith & Robards even offered up these wild gizmos for sale ... but the very nature of mad science is that the devices created by it require the help of manitous, and therefore defy attempts at mass production. The key behind mad science is that it is inherently supernatural, and therefore not true science.
Mad scientists are still around, but not in any great numbers -- aside from think tanks responsible for making nifty spy gadgets for British Intelligence agents, or super-weapons for the Nazis. Most mad scientists are loners by nature, living and working and dying in obscurity, along with their wild inventions. Any Mad Scientist in the Posse, of course, can be an exception to that rule, but he'd still be well-advised to keep a low profile, or else he's going to get an "offer" to join one of those think tanks. Sure, being chased around by Nazi, Confederate and Union agents could make for a fun adventure, but eventually they're going to catch up.
That said, the rules for Mad Scientists are unchanged since the time of the Weird West. The only thing that has changed is the list of examples of inventions that would fit in each category. Cars, trucks, machine guns and even airplanes now fall under the category of "top-of-the-line technology" at worst. "Jacks" are sufficient to come up with a number of devices that would have required as much as a "Full House" in the Weird West. Those items that would have been classified as "New technology that flaunts the laws of science" (heat ray, etc.) or higher are still just as hard to attain, however. The laws of physics haven't changed -- just the baseline of what's currently available in the world of real science.
Blessed, Martial Artists, Hucksters, Shamans and so forth are treated the same way in the early 20th century as they were in the Weird West. It's just that any such members in the Posse will be more unique than they were in the Weird West.
If the character is actually from the Weird West, he should have the Veteran of the Weird West "Edge", using the table from the Marshal's Handbook. Don't use the table from Hell on Earth. That much time hasn't passed yet. It's entirely possible for a Weird West hero to still be kicking in the 20th century, even though he may be a Codger , with related Hindrances, such as Ailin', Bad Eyes or Bad Ears. For instance, a hero who was 20 around 1887 would be 70 by 1937. There's no need for time displacement, "Omega Man" or being Harrowed to still be in the game.
Characters with Arcane Backgrounds and special powers from the Wasted West may be in for a few nasty surprises if they travel back to the 1930s.
First off, the world hasn't yet been saturated with supernatural energies, so only Harrowed can Count Coup on Abominations. After the Last War, everyone can Count Coup, but if they go back in time before then, they may well lose those Coup powers -- at least, that is, until they hop back into the Wasted West again.
It's ultimately the Marshal's call, but here are some suggestions on how to handle it.
If the Coup power is something that would normally be available to anyone -- not just Harrowed -- then it's unaffected. (An example would be the so-called "coup" of obtaining a Jackalope's foot.)
If the Coup power is some sort of resistance or other effect that pertains only to the supernatural, then it's not affected, either. (An example would be if you defeated a Servitor of Pestilence, and gained special immunity to the supernatural disease spread by that Servitor. It's a very special-case situation, likely to be moot in the past anyway, and in ordinary everyday life, it has no effect whatsoever.)
But Coup powers with overt or even flashy effects are almost certain to disappear when traveling back to this period. The supernatural is at ebb tide, after all!
Doomsayers definitely get the short end of the control rod. The world hasn't yet been saturated in the Glow. Except in the unlikely event of being exposed to large amounts of radiation, their powers disappear while in the past. Doomsayers still retain the power of Resistance. At the Marshal's call, there may be certain instances in which they may regain some or all of their powers, if they are exposed to large amounts of ghost rock radiation ... but considering that irradiated ghost rock was not in wide use in the early 20th century, that's not likely to happen.
Of course, since Silas Rasmussen hasn't even been born yet, there's no reason for a Doomsayer character to be native to this time period, and there's no way for a time-displaced Doomsayer to initiate a convert into the ranks of "The Glow" in any supernatural sense.
Toxic Shamans get a bum deal, though not nearly so bad as Doomsayers. First off, they'd best leave their Totems back in the future, unless they plan on staying in the city. If a Toxic Shaman wanders into any sort of wilderness, his Toxic Guardian is going to get waylaid by a bunch of nature spirits. The nature spirits may not be as strong as they were in the Weird West, but they're still by far healthier than in the future, and toxic spirits are few and far between. Toxic Shamans have to add +4 to the TN of all rituals while in urban areas, +6 in polluted wilderness, and +8 in pristine wilderness. Regaining Strain is going to be nigh impossible for Radiation Shamans. Smog and Trash Shamans would be more at home in Junkyard. Even if a Shaman can find a source of pollution to wallow in, he regains Strain at half the normal rate.
Toxic spirits native to this time period are not powerful enough to become Toxic Guardians, the Coyote Confederation hasn't developed into a toxic wasteland yet, and the nature spirits are still on top, so Toxic Shamans are not possible as characters native to this time period.
Templars are not as bad off as they'd be if they went all the way to the Weird West. At that point, their Saints would still be alive -- or perhaps not even born yet. Templars have +4 added to the TN of all their powers, and they get no benefits bestowed by Martyrs, because either the Martyrs aren't martyred yet ... or else their powers have not yet manifested. (It should be noted that "Armor of the Saints", not having a TN, is unaffected by the time change.)
Anti-Templars have problems with the time displacement, but for different reasons -- the Reckoners are being more stingy with their powers. The same penalty applies to an Anti-Templar: she gets +4 added to the TN of all her powers, and does not have access to any additional powers bestowed by the Reckoners.
Templars and Anti-Templars can't make any "new recruits" in the past. There aren't any ghost rock storms to go through as a rite of passage, for starters. Any powers they retain are just holdovers of what they experienced in the future of the Wasted West. Therefore, Templars and Anti-Templars native to this period are not possible.
Junkers don't fare so well, since the world is not full of "tech spirits" for them to draw upon ... though it's not nearly so bad as if they'd been dumped in the Weird West. The TNs for any rolls to create new devices are increased by +4. Miniaturization is not an option in this time period; everything is big, clunky and unwieldy, and any tech spirits the Junker manages to contact can't really imagine it any other way. What's worse, though, is that irradiated ghost rock isn't to be found here. Unless he brings a sufficient supply of ghost rock batteries with him, or his devices are powered by spook juice, a Junker won't have any fuel to use his inventions.
While the Nazis do make some headway into the realm of Junker science in the 1930s, Junkers do not exist as natives to this time period. It's still the realm of Mad Science.
Sykers from the 21st century have it pretty good, all things considered, since they draw their energies directly from the Hunting Grounds. Their powers, therefore, are unaffected by time-displacement.
Sykers native to the early 20th century are at somewhat of a disadvantage compared to a time traveler, because their art has not yet been fully perfected ... and, what's more, any Syker is going to be under the thumb of major world governments. A Syker in this time period has access only to a very small number of powers. The rest just haven't been developed yet. (The Marshal, as always, can make exceptions, but basically the brain-blasting, bone-ripping, fantastic powers of Sykers in the future are far beyond those in the 20th century.)
Powers permissable for a 20th century Syker include: Arson, Fleshknit, Mindrider, Mindwipe ... (list to be expanded later)
Witches from the Wasted West are unaffected by time displacement. How to Serve Your Man was published in the 1960s -- well before the Last War -- and Ms. Devlin had been practicing her craft well before that.
As for Witches native to this period, there aren't any in the strict sense of those found in the 1960s onward. After all, How to Serve Your Man hasn't been published yet. The only Witches of this type are direct descendants of Mina Devlin.
Cyborgs don't have an Arcane Background, per se, but it's still relevant to discuss how they may be affected by time displacement. First of all, unless the Marshal wants to have there be some nasty side effect of the method of time travel itself (such as, "all electronics carried by the time travelers are fried"), the Cyborg should not be adversely affected. His systems are powered by the Manitou firmly trapped thanks to the Spirit Harness. The main difficulty he'll run into is in the lack of spare parts ... and, for Combat Cans, the tricky business of trying to pass for human. The days of getting cyber-mechanical body part replacements at Junkyard have fallen into obscurity -- Heavy Cans and Drones are likely to be seen as nothing short of monsters, and treated accordingly in just about any culture. (Well, except maybe in Nazi Germany, where the Cyborg will be destined to be disassembled and studied to further Hitler's war effort.)
For the Cyborg who covers the problem of passing for human or at least keeping out of sight, there's also the matter of self-repair. The Manitou takes care of any problems with a fuel source, but spare parts are going to be hard to come by in a time before they were even invented. Therefore, the TN of any attempts to scrounge for spare parts (or, more likely, raw materials) for self-repair is increased by +4.
Not surprisingly, there are no opportunities for Cyborgs native to this time period. The Spirit Harness hasn't been developed yet, let alone all the high tech gizmos built into most Cyborgs.
Harrowed exist in the Weird West, the Wasted West, and everywhere in between, though they're best off not letting on about their true nature. Fortunately (for them), the Great War went a long way toward producing lots of horribly disfigured veterans, so a great deal of mileage can be gained by passing oneself off as a war veteran, and wrapping oneself up in strategically placed sections of gauze, to cover those unsightly death wounds. Harrowed powers (and Coup powers) are unaffected by time-displacement.