They have ventured in to historical periods, notably The Great War and more recently Trafalgar. I've used Great War but found them to be too dice heavy for my tastes. Saying that, the booklets are well produced, informative and a good read. They have a great support network, with foums and Q&A sites, also they produce supplements so you're never stuck for choice.
As I said not for me as I don't do S-F/fantasy and I find the historical stuff not to my taste, but a lot of friends rate the game mechanisms and playability. I've got their books on my shelf so although I don't play their rules and I do enjoy reading them.
Have fun!!