Honestly, I don't know that ETHex is the first gambling platform that fully operates on Ethereum network or not, but the platform has grown very strongly months since its start day. I am one of participants of ETHex signature campaign months ago, and still keep observing the growth of this platform. There are many gambling platforms that accepts Ethereum as one of coins to gamble and withdraw, but it seems the platform is the first fully Ethereum-operated gambling platform. Please correct me if I am wrong.