It's been said that it's not possible to write a completely original story anymore, that they've all been told and it's just a matter of reworking things with a new twist. I'm having an issue with adding that original twist, and I'm trying to decide how much I should be worrying about being original versus just writing what I want to write. I'm taking a break from my fantasy/magic story and want to try at sci-fi. Problem is, the tech/setting/ideas are heavily influenced by "Earth: Final Conflict" (EFC) and "Stargate" series. For example, the basic background is that two very high-tech civilizations were waring way back when, one purposely build a doomsday weapon that destroyed all biological matter across the galaxy, but then seeded worlds with something that given a wide range of evolutionary pressures would give us our standard humanoid people. Right there we've got Stargate's Dakara Superweapon or Star Trek's "The Chase" episode. The purpose of starting out that way is to give Earth a present-day setting while giving the secret government labs high tech that they're just sorta stumbling their way through. When the story starts out, it's with Earth's first interstellar spaceship, malfunction happens with the engine, and they emerge in the middle of a shootout between two other races. Barely escaping back to Earth, they realize WTF they got into and change tactics to more nearby survey missions to try to gather materials and more tech so they can survive. Very Stargate like. I also want to explore bio-energetic lifeforms, similar to EFC. I realize one issue right away is that I need a stronger motivation to get a plot going for a novel as opposed to a TV series-like thing, but in these rough thoughts, perhaps you can see my point? Should I worry about effectively copying what's been done to make my own thing, or should I just go and write it, and not worry about seeming to borrow from what other authors have done?