Explore the intricacies of cryptocurrency security in this 21-minute ACM conference talk that introduces and analyzes the "gap game." Delve into a comprehensive study of blockchain systems, examining proof-of-work mechanisms, mining incentives, and the formation of gaps in the mining process. Learn about the combination of symbolic and numeric analysis tools used to evaluate various scenarios, and understand the implications for Bitcoin and other cryptocurrencies. Gain insights into mining profitability, centralization risks, and the evolving role of transaction fees in the blockchain ecosystem.