Like what @carlfebz2 said, I hope you consider adding other altcoins for the convenience of users because high fees are often the gambler's concern.
OP has said they are planning to add Litecoin on next month. That shouldn't be any issue with fee anymore.
good to see any option altcoin deposit such ethereum, how much minimum deposit?
and I read AML Policy, are the user must proof the passport or any kind of identity such ID card?, because by experienced any kind of exchange, did not accept except the passport.
I don't see any min deposit, but it would be better to deposit at least $0.1 since most of games i've seen use that amount on rollbit.
Any deposit amount will be converted to $, so if you send any bitcoin or ETH, it will be converted to $.
From Rollbit's Terms of service
This identification relies on the following fundamental principles:
A copy of your passport, ID card or driving license, each shown alongside a handwritten note displaying six, randomly generated numbers. Also, a second picture with the face of the user/customer is required. The user/customer may blur out information to secure their privacy, besides date of birth, nationality, gender, first name, second name and the picture.
You can pass the KYC with other ID beside passport.