These aren't BTC-focused games. It's normal games from non-crypto-related studios that decide to implement Bitcoin rewards because it improves their retention and monetization KPIs. If they could do it with USD, they would. But they can't, because it's shit money. Bitcoin is the best money, especially for this specific use case (sending tiny tiny amounts of money to anyone in the world instantly through a game).

Most studios live on ZEBEDEE right now are indies that had games that didn't perform well, so they added Bitcoin-powered player rewards. And wouldn't you know it, the games got massively more profitable and successful!