Every project may have multiple custom currencies. For example "diamonds" and/or "cash". Aside from these typical game currencies, projects wishing to sell NFTs must integrate a specific currency. The internal name for this currency is "rgn-coin". When the "rgn-coin" is presented in the UI it can have any currency name, for example, "gems".
The "rgn-coin" can only be sold using in-app purchases. For more information, please refer to the Currency GDG.
Other typical currencies can be added and used in an expected manner - as rewards to the user's account, or sold for in-app purchases.
Purchasergn-coin (IAP required)
Purchasing rgn-coin works a bit differently, it has its own API called PurchaseRGNCoinAsync(string iapUUID)
You will need to get the transactionId and receipt when the in app purchase is completed.