999dice is not provably fair and accused a scam.
seriously ? can you give some proof of witness ? 
because i am scared now How 999dice.com is stealing your coins, and exactly why you won't believe me
TL;DR: 999dice is not provably fair at all, but they hide is so well, you'd never actually know it.
999dice SCAM exposed
Quote
If you are on a luck streak their defrauding algorithm will try to trick you into betting a huge amount and then hit you with loss after loss.
Google for more
Disclaimer: All those articles are from mid-2015, if in the meantime something changed with 999dice, they don't cover that.
However, I don't bother to take a look at the site given it's past state as described in the post/article.