Nothing wrong with looking at someone else's 'verse and saying, "yeah, I'd like to do something like that". Whether it's Mass Effect or Star Wars or Star Trek or Middle Earth, they don't have the monopoly on their respective genres.
If you wrote a story with original characters set in a "Galaxy Gonne Madde" or torn by war or whatever, you can use whatever names you like for your factions, your planets etc and make it your own.
You may think "OK, I want this world to be rather like Tatooine" but when it boils down to it, it's just a desolate rock of a planet where people eke out a miserable existence, so you could call it "Foozbing" for all it matters and if you want to make departures from what the original Tatooine is like, you can (e.g. your world has a Crystal Spires and Togas type civilisation in one area, contrasting the subsistence-level Crapsack elsewhere on the planet) without breaking the canon of someone else's 'verse.
Original characters, original worlds, same basic idea/premise - be it Space Opera, High Fantasy, Noir etc.
I find world building can be like character building - it can just "organically grow" as you're typing/writing. Your mind's on the world and the characters and brewing away then suddenly you find you've written something that makes you think "aha, that explains why such-and-such is the way it is" or "wow, this opens up whole new possibilities for my characters".
Even easier if you're familiar with the genre as your mind will have a wealth of information about how things might "work".
Just keep notes as you go to ensure continuity/consistency. You don't have to sit down and plan every little detail about the universe or a character right at the outset - it works for some people but for others (like me), it takes over and rapidly becomes an excuse not to do any actual writing. Can't write that scene yet, I haven't finished working out my protagonist's equipment, skills, back story, romantic interests, personality traits...
Start with the broad strokes - which you have - and then add the details later as they become relevant or evident (going by what's just happened on page 24).