Gemmell esque settings. The Waylander books seem like standard low magic fantasy stories until you include future technology, mutants and time travel. Jon Shannow includes that and western setting, post apocalypse and demonic hordes, even using magic to flood the world and raise the titanic.
Unfortunately David Gemmell was quite determined that his stories never be translated into films or tv as he didn't want anyone messing with them but for a serial number filed off setting they are quite good.
Druss stories less suitable. He is a strong guy who turns his enemies into mince by the horde load with a demon inhabited axe. Every story more or less translates into low fantasy alamo, entertaining but you can only do the victory against overwhelming odds thing a few times before it gets stale.
Away from Fantasy, filed off serials of Buck Rogers, Flash Gordon, Blakes 7, X Com (invasion of earth, getting ass kicked, adapting their technology and taking the fight back to them. It would be a high fatality total party kill setting for a while until the PCs can break through to gain skill/gear they need), War of the Worlds, some kind of Undersea war/land that time forgot with Dinosaurs, Highlander, Starship Troopers, Battlestar Galactica (fleeing from nigh invulnerable enemy and coming across indications that this sort of thing has happened before).
Heck, even make up a chart and roll on it, combining horror with fantasy (undead apocalypse in high fantasy elmore land), Sci Fi with Super Heroes (legion of Supers take on alien invasions), Western with Kung Fu...
Oh wait that's like Far West. It'll never happen.
(Yeah I know it's in the 'final stages' according to the latest waffle but it's been like that for 11 years)