The level of hazard you'd encounter probably varies wildly. It would depend on what part of North America you're talking about; large parts of the continent are effectively undefined because the players running those areas packed in and never did anything other than plop down their rudimentary exercise in nation-building.
Most nations are playing at what I'd call medium-magic. It's not high-magic, in the sense that technology, weapons, and logistics are mostly defined by mundane constraints. On the other hand, you have the Aztecs whose gods actually walk around screwing with people on a regular basis, and even the 'low-magic' nations tend to do things like enchant their cannonballs to hit harder.
However, almost arbitrarily powerful magic can fit into the setting, and several nations combine (pre-1800) technology and magic in interesting ways. My own country is one of the lowest-magic nations in the setting, and gets away with it because its star-worshipping religion works well enough for active divine intervention to block most uses of magic against the Ohioan people.
As to who's who... of the players who have at least done something
active enough to be noticeable and really considered a player in my personal opinion...
Maddoc is playing savage hyenorks who live north of the Arctic Circle, mostly.
Zwinmar is playing the Thyrs in the central part of the OTL Great Plains.
The Romulan Republic is playing elves in OTL Vancouver, roughly.
E_F is playing Orion in OTL Quebec.
I'm playing the Ohioan Empire in the midwestern parts of the OTL United States.
Esquire is playing the Ottomans along the west bank of the Mississippi
Beowulf is playing the Dragon Kingdoms (?) which cover the OTL Deep South of the US, and much of the Caribbean.
Raw Shark is playing the Aztecs in OTL Mexico
Crazedwraith, UPCinnabar, and Abacus... I do not think they've clearly defined what they want to play.
All the nations above, except for the elves in Vancouver, the hyenorks in the far north of Canada, and the thyrs of the Great Plains (think WoW orcs with iron discipline) are basically human.
There is at least some prior information affirming the existence of goblins and dragons. Anything is fair game, really. I have referenced there being, in various times and places, ogres, mermaids, giants, extraplanar demons, and probably other creatures unknown and unknowable. And that's just me personally- but I tried to be nonspecific as to where those creatures resided and so on, so as to leave others' options open.
As to holes in the map...
We've got Imperial528 who says
he's playing a confederacy of nation-states around the Pennsylvania/New York/Massachusetts/Vermont/New Hampshire area, but he has literally never done anything I can remember to interact with other players. I'd be in favor of replacing it with a new player nation-state if you seriously intend to participate; it'd help fill in a major gap.
We've got an NPC (orphaned player state) centered around the Chesapeake Bay, but it could be brushed aside if you want to use that real estate.
Another hole in the map is down by Texas. AMT staked it out but never did anything with it that I can recall.
And yet another, west of Lake Superior, including the Dakotas, parts of Wisconsin and Minnesota, and stretching north into Canada. That used to be the player nation-state of Assiniboia, but that has gone defunct even when I repeatedly contacted the player running it asking for information pursuant to an attempt to collaborate.
Jub is playing the Sylix, magic-empowered Native Americans, in the northern reaches of the Rockies. We haven't heard from him in a long time either.
Panzersharkcat had something going in southern Alaska- again, incommunicado... pretty much everything more than a few hundred miles west of the Mississippi has just about dropped out, really.
I forget who's playing Fusang, or the goblins of the Rockies, or the necromancy-dominated state of Tarn that was supposed to be around in the Colorado Plateau. All those are pretty well abdicated, I guess.
Formally TRR is the mod for this game, but I thought I'd fill in on the facts.