How does Bitcoin Gold implement replay protection? The creators of Bitcoin Gold claim that they have implemented full replay protection. How does this replay protection work?
I don't believe any replay protection has yet been implemented, they still have an issue open for it on the BitcoinGold repository here:
https://github.com/BTCGPU/BTCGPU/issues/51

I haven't dug into the code itself but I would imagine that they would have closed the issue if they had implemented something.

The statement by Bittrex also claims that they haven't implemented any replay protection: https://support.bittrex.com/hc/en-us/articles/115002320451-Statement-on-Bitcoin-Gold-BTG-

Update as of 3rd November 17:
A PR for replay protection has been merged, https://github.com/BTCGPU/BTCGPU/pull/109

They announced it via twitter here: https://twitter.com/bitcoingold/status/925600171425259520

It uses a new SIGHASH_FORKID to implement the 2-way replay protection.