Bitcoin GoldBTG
The October 2017 fork that switched to GPU-mined Equihash, and later suffered repeated 51% attacks.
The magazine's angle: a fork sold as “one GPU, one vote” whose public face ran a mining-hardware shop, and whose low hashrate made it a textbook case of what a minority proof-of-work chain risks.[1]
Launch
Bitcoin Gold took a snapshot of Bitcoin at block 491,406 on 24 October 2017, but its first own block, 491,407, came on 12 November 2017, nineteen days later[1]. Holders at the snapshot received 1 BTG per BTC[1].
GPU mining
The fork replaced SHA-256d with Equihash (200,9), the algorithm used by Zcash, and moved to an Equihash-BTG variant at block 536,200 on 3 July 2018[1]. Unlike Bitcoin Cash, it kept SegWit[1].
People and endowment
Its founder and public face, Jack Liao, was chief executive of LightningASIC, a Hong Kong seller of mining hardware[1]. The first 8,000 blocks were mined at minimum difficulty to a 4-of-6 multisig, creating a 100,000 BTG endowment[1].
Attacks
In January 2020 two reorganisations of 14 and 15 blocks double-spent about 7,000 BTG combined; in July 2020 an attacker mined a 1,300-block private chain, which developers rejected with a checkpoint at block 640,650[1].