another useless altcoin they created by using bitcoin's source code and its blockchain. in other words they forked from bitcoin.
and so far it seems more like a scam rather than a real thing. they haven't even made any source code for it.
http://www.btcd.io/index.html the link at the bottom of the page to Github is empty!
there is no wallet, no actual change apart from increasing the cap from 21 million to 210 million. and people have been dumping it even since they got their "Future" tokens in some exchanges!!!
https://coinmarketcap.com/currencies/bitcoin-diamond/