I read (don’t know exactly where but it was on epic website) that it depends on what you give to the backers. I will put some examples:
- If they give some money and you give them a poster, you don’t need to pay anything.
- If they give some money and you give nothing, you don’t need to pay.
- If they give some money and you give the game either on physical or digital edition, you pay the percentage.
So as you see you will need to pay royalties only from the actual tier where you give away the game.