Pulp Alley is a really good choice. You can use it for anything from stone age to futuristic sci-fi. You can range anywhere from totally historical to totally fantastical, and Pulp Alley seamlessly integrates historical and fantastical elements in one robust system.
I say its robust because you can bend and twist the rules without breaking them. The engine of opposed dice throws of multiple d6, d8, d10, and d12 can accommodate a wide range of different character abilities. A "league" can range from a single epic character to many figures using gangs and gun or vehicle crews, so you can make it look as military as you want it to look. The cards add some nice twists of fate or challenges, but you can deemphasize them by limiting the number of cards that players can hold in their hands.