Someone wants to use one of my fonts for a game they will sell in the app store. I usually charge 10 bucks for a font, but i feel like i should be getting a percentage of the revenue once this person starts selling the game. Idk how things like this really work:/

Make it $0.5 a sale, that is far from over-asking and still might make you some money ...

(usually a basic app is sold about 0.79€, and 30% of these 0.79€ will be paid by the author to the market... so 0.5$ per sale seem expensive)

How do you plan to control the sales of the game ?