Ethereum (ticker: ETH) was founded by Vitalik Buterin in 2014 and is the 2nd biggest cryptocurrency by market cap. It had one of the first ICOs, raising $5.2 million. Whereas Bitcoin's blockchain is used primarily as a ledger of account for payments and value storage via BTC, Ethereum's Turing complete system is more versatile, used to securely track a wide variety of assets (smart property) and even contractual agreements (smart contracts). It initially relied on proof-of-work, but is now transitioning to proof-of-stake.
These factors have made Ethereum the most popular platform for blockchain gaming developers, with most relying on MetaMask and Infura. Many major blockchain games and gaming platforms use their ERC-20 standard for their featured cryptocurrency. The ERC-721 and ERC-1155 token standards are also most commonly used for NFTs, especially tokenized cards and items for blockchain games. Smart contracts could also be used to build a fully decentralized online game, but currently transaction fees make this unfeasible. Many blockchain games have migrated to sidechains such as Polygon to counter the scalability problem; protocol developers are also working on various other solutions.