I am looking to buy this game (along with the expansions).

But since my gaming group only get together once in a blue moon, I was wondering if there were any solo rules out there?

Thanks in advance.

Not yet! Not that I'm aware of anyways. Sorry!

There are no official solo rules, but there are quite a few solo or cooperative homebrew variants floating around; I believe the Variant subforum on BGG has at least half a dozen.