Weird War II is pretty common. There's a couple Weird War I things that I can think of. But you don't often see too many Weird Colonial Times material. So, if you want to play in such a setting, you migth want to check out the Strange New World Gazetteer. It's a new RPG Zine that's up on Kickstarter now.
From the campaign:
Strange New World is an OSR-compatible campaign setting set during the colonization era of North America (1600/1700's era) but set in a world where magic, monsters and, more importantly, strangeness have returned to the new world. Soldiers and monster hunters fight side by side trailblazers and mountaineers. Witches weave terrible magics while preachers vanquish chaos and shepherd the people.
(Strange New World content is compatible with any WhiteBox / B/X / BECMI or AD&D system, we use a hacked version of Lamentations of the Flame Princess as our OSR base. SNW content could even be used with OSR-adjacent games such as Dungeon World.)
Compared to a traditional fantasy world, the Strange New World is a points-of-light setting. Colonization of the new world has slowed and exploration in many regions has ceased after proving too risky. There are fewer settlements than there were in actual history and they are spread very thinly through the perilous frontier. The land rages against colonization, it cracks and leaks hellfire pockets of poison gas, it births powerful megafauna guardians, and summons woeful bogeys from the fey realms in efforts to protect itself. Society has instead packed itself into well-protected cities, increasing urban population above historical levels, while spending more resources on military outposts and organizations opposed to the chaos of the new world.
This is also a world where gonzo weirdness has found a home in history. Ancient alien visitation shaped the beliefs of the native people, once-mighty and now-lost civilizations that existed thousands of years ago in the new world are there to be discovered or pillaged. This is a world where fables and folk lore are not merely cautionary tales but historical accounts. A world where the mythical Underworld is a real land of the dead that can be visited. Strange New World also exists in the meta-setting of 400 Billion Suns, where "billions and billions" of possible worlds could have interacted with each other through the magical eons.
Monsters, magic and bedlam must be dealt with before man may progress in this Strange New World.
The campaign's closing in on 4x funded, but there's only less than 3 days to get in on the action.