BTG is full name BitcoinGold, which is also called BitcoinGPU. Its origin is an activity initiated by developers to oppose segwit2x: "NO2X".
BTG is a new digital currency obtained by hard forking the Bitcoin blockchain. Its main features are:
Similar to Bitcoin Cash, BTG will also add SIGHASH_FORKED (a security mechanism after hard fork).
BTG will be pre-mined. The BTG blockchain will initially mine in a non-public environment, which means there will be an initial allocation to early developers and supporters.
BTG will use the Equihash PoW algorithm. The difference between this algorithm and the SHA256 used in BTC is that the hash computing power will be affected by the memory size of the computing device. Therefore, ASIC miners will no longer be effectively used in BTG mining.
The founder of the BTG project is Jack Liao, the founder of Lightning ASIC. The company that developed Bitcoin Gold Bitcoin Gold is headquartered in Hong Kong and is headed by an anonymous developer named "h4x3".
BTG is a hard fork of Bitcoin BTC. On October 24, 2017, it was split with Bitcoin after the birth of Block 491407. The BTG blockchain will initially mine in a non-public environment, which means there will be an initial allocation to early developers and supporters.
BTG uses the Equihash PoW algorithm. The difference between this algorithm and the SHA256 used in BTC is that the hash computing power will be affected by the memory size of the computing device. Therefore, ASIC miners will no longer be effectively used in BTG mining. However, Bitcoin initially advocated its goal of decentralization. At present, only a few mining machine manufacturers produce mining machines, so their computing power is monopolized by mining machines. Mining machine manufacturers undoubtedly seized control of Bitcoin, which was contrary to their original intention.
To change this situation, Liao Xiang and his team hope to create a digital currency to "anti-ASIC", a digital currency that does not require expensive, advanced mining hardware ASIC, which is later BTG. Unlike the previous more successful Bitcoin hard fork - Bitcoin Cash BCH, BTG is not used to replace Bitcoin. Seen from BTG's white paper: "Bit gold emerged to protect Bitcoin and to ensure its status as a major cryptocurrency."

Project Highlights

1. Decentralization
Bitcoin Gold uses a PoW algorithm, "Equihash", which cannot run faster on dedicated devices for Bitcoin mining (ASIC miners). This gives ordinary users a fair opportunity to have a ubiquitous gpu.
2. Fair distribution
Distribute Bitcoin’s blockchain fairly and effectively, and immediately distribute a new digital asset to people around the world who are interested in Bitcoin. Other ways, such as creating coins with a new Genesis block, concentrate ownership in a small group.
3.Replay Protection
To ensure the security of the Bitcoin ecosystem, Bitcoin Gold has implemented complete replay protection and unique wallet addresses, which are the basic characteristics that protect users and their coins from multiple accidents and malicious threats.
4. Transparency
Bitcoin Gold is a free open source software project built by volunteer developers and supported by a rapidly growing community of Bitcoin enthusiasts.
Application Scenarios
1. The assets of immigrants overseas are transferred, breaking through foreign exchange restrictions, and eliminating the troubles of relatives and friends from going to the bank to buy foreign exchange or buying foreign exchange in the black market.
2. Preservation of value of severe inflation
BTG's current problems are:
BTG has not yet fully reached a consensus code, does not have a replay attack protection mechanism, has not conducted sufficient code testing and review, and has no named code developers.
At the same time, the BTG code base also contains 8,000 (100,000 BTG) of private pre-mined blocks. Developers may sell their pre-mined BTG on the open market.
As of October 21, 2017, BTG has not applied the above SIGHASH_FORKED security mechanism, and the development related to algorithm changes has not been completed. The date of the hard fork and the initial operation of the BTG blockchain have not been confirmed yet, and whether new blocks will be stable in the future are still uncertain.

BTG has encountered two 51% attacks

51% attack + double payment means that an attacker uses double payment to send two transactions, using his own currency to trade one to others and transfer money to himself. After the transaction with others and the equivalent exchange is completed, the attacker launches a 51% attack, invalidating its transaction with others, while the items exchanged by others and themselves are still in the hands of the attacker.
On May 16, 2018, Bitcoin Gold (BTG) encountered a 51% attack.
The attacker's approach is probably like this:
1. As a miner, one day I temporarily mastered more than 51% of the computing power.
2. Recharge a large amount of BTG to a certain exchange.
3. At the same time, the miner mines on his own BTG private chain and excludes the transaction recharged to the exchange on his own chain.
4. Quickly sell the BTG coins on the exchange and withdraw cash and leave.
5. Since the miner has a lot of computing power, the chain he dugs himself is longer than the main chain. After broadcasting the private chain, it becomes a new main chain. The new main chain no longer has the transaction of exchange recharge coins.
6. The exchange inexplicably lost 8,000 BTGs that do not exist on the main chain.
The miner launched 17 attacks in four days, spending 20,500 BTGs in a total of 4 attempts, and the exchange suffered heavy losses.
On January 23, 2020, Bitcoin Gold (BTG) was attacked by 51%, and $72,000 was spent on double spend. This is the second time Bitcoin gold has been attacked. In the latest attack, the attacker reorganized the blockchain network twice after controlling 51% of the computing power, spending 1,900 BTG (about $19,000) the first time and 5,267 BTG ($53,000) the second time.