Just make the games core currency based around it. Its no different than Gold in WoW or Plat in Warframe. You can even pool coin into a wallet where it goes to players for rewards for simply playing the game.
edit: Going to call it now, In 5 years this thread will look like a total joke. "Who would even use something like this?
HAHA
Hear me now quote me later, you wont be able to get away from crypto currency once people integrate it into gaming. There will be a day when people playing games are confused that grinding money in MMOs wasn’t for real money ect.
edit 2: This reminds me a little bit of when people down talked the internet like it was a fad. Or when IBM didnt think anyone would ever want to use a “Mouse”
But yeah having some kind of integration for crypto in UE4 is probably a good idea.