Wow! Thanks for the response here! I didn't expect to receive this much help! I suppose I need to clarify some things that I said in my original post. I didn't have a ton of time and didn't want to bog this down with a whole lore dump but I see now that more info is better.

SO.

The first campaign started at the beginning of what has been called The Mist Crisis. An otherworldly mist erupted from a series of ancient tunnels that crisscross the landscape. It made people behave strangely and began to affect the wildlife among other things. Basically something deeply wrong had happened to the world and this was its way of retaliating. I didn't really let on to what this was but the one player who I spilled the beans to would obviously know in some way what's going on. That's both a plot thing AND a feature of the world. It's a high weirdness environment but the players enjoyed it and I'd really like to see it explored a bit more. The subsequent tries at this setting basically just moved that event into the past.

That's a big point of struggle for me... Do I include that event in the history of the world or do I have it come into play after the campaign gets going? Or just not include it at all? There's a couple fundamental parts of the world tied to this and I don't need to include them but I like them?

I think the another big world building problem I had was basing the cultures of the world too much on real life things and it got a little stereotypical. It wasn't the worst but I'd like to do a better job of having interesting culture in the game that isn't just "welcome to fantasy Mongolia where the orcs are in charge"

My lunch break is over so I'll try to add more later