it removes my exclusivity of ownership over my own code.
Your statement is false. It does not remove or diminish your exclusivity of ownership over your own code. That’s just not how copyright works. I don’t know how else to put it.
I’d gladly pay them a smaller fee
If I ever wrote code you wanted to use in a game you wanted to sell, and you reached out to me, I’d just let you use the code under a different license for free. My main concern is that corporations would freeload off my work. Some people wouldn’t even do it for any fee. I think that’s silly, but they get to set the terms of how we use their code.
selling copies of my software is largely how I make money
That’s great! You are part of a tiny group of people who manage to make money this way, and that’s no small accomplishment. More power to you, and I wish you more success. If you feel comfortable revealing it here, what game(s) do you sell?