How much revenue does Gog make compared to valve for instance?
I don’t know. That’s not relevant to the definition of a monopoly. To be a monopoly you need to be the only supplier of a product or service. If there’s competition, but you have the majority of market share, then you’re merely dominating the market, which is not illegal (or even necessarily a bad thing, as evidenced by Steam).
Google Play and Apple store are monopolies because they are not competitors to each other, if you own a phone you’re stuck with one or the other with no choices. They also take steps to prevent competition, which is highly illegal.
I don’t know. That’s not relevant to the definition of a monopoly. To be a monopoly you need to be the only supplier of a product or service. If there’s competition, but you have the majority of market share, then you’re merely dominating the market, which is not illegal (or even necessarily a bad thing, as evidenced by Steam).
Google Play and Apple store are monopolies because they are not competitors to each other, if you own a phone you’re stuck with one or the other with no choices. They also take steps to prevent competition, which is highly illegal.