Dammit, this is getting to be a bad habit for me...I'm backing another Kickstarter. But: the Troll Lords are very consistent and reliable in their Kickstarters, and their books for the last couple of years now have been stellar productions. Also, I bought Codex Nordica which Brian Young (the author of the three books in this KS) wrote, and it's really, really good stuff; I'll be snagging Codex Celtarum soon.
C&C Mythos is actually a KS for 3 books: Codex Germanica, Codex Slavorum and Codex Classicum. Together it sounds like you could have the full workings of an ancient mythic Europe campaign. Now, if they are contextually like Codex Nordica then you can expect a series of books laden with the flavor and mythology of each setting, and an emphasis on the academic historical elements....you could in fact use Codex Nordica for a straight up traditional historical game if you like, but its really aimed at something larger than life and more mythic; the world as traditional Vikings thought it was, rather than just what historians knew it to be.
So...Mythos. Check it out: