Well, there a some other RPG games that rewards you with cryptocurrency...
Whats so special with this one?
All the games that usually make this type of system, what they do is use the power of your device to mine an existing currency to give you then a small portion.
In this case, the system is different, and I have not seen any that offers you a coin at the expense of playing.
When you said device what you mean is computer right?? Not smartpones? Becaus if you knew some kind of application that can be mined through phones, please share it to us I really want to do so.