“Write your own magic system.”
That’s what Darryl Schweitzer told me years ago, after I had submitted a pretty egregious Lovecraft pastiche.
“If you do not get the details right, someone will make note. That adds an additional burden to your tale.”
That last part was a paraphrase, but I believe I captured the spirit. Maybe I even invented that part because I have learned that to be true: with a pastiche, the best you can hope for is building something impressive in someone else’s sandbox.
I’m young enough and egocentric enough to think I can do a good job on my own world building.
Mind you, when a writer is starting out, a writer MUST study and model the style of their favorite writers. But there is a difference between (to use a music reference) Brian Wilson studying The Lettermen and making their style into a new sound, and Noel Gallagher doing the same to John Lennon and making 2nd rate John Lennon.
A style comes with talent, practice, and aspiration. No writer can control innate talent. Writers can put in lots more practice and get plenty of rest and study other works to improve.
Aspiration is a whole ‘nother thing.
How distinct do you want your work to be?
How much of your own voice, that secret and heard only by yourself voice, is in your work?
Does your idea remind you of someone else’s idea? What new twist can you bring to that idea? A twist that gives you a thrill and makes you say “cool!” and “I’m not sure anyone else will like this.”
Does a character you write remind you of something you’ve read or that distinct person you know personally?
By writing your own world in your own voice, I believe you add to the dialogue of civilization. Your work can be both enjoyable to write and also challenging to yourself and to your reader. Editors tend to like stories that are different and provoking.
For the record: read and write whatever you want. Also, there are far better and more accomplished writers than me who write pastiches. One of my favorite stories is “A Colder War” by Charles Stross, a Lovecraft political parody.
But when one of the foremost Lovecraft scholars told me to swing for the fences, I’m inclined to listen. As a result, my writing experience has been more rewarding for me, has better impressed editors, and has gotten enthusiastic response from readers.