One of the distinct properties of public blockchains is transparency. We use the property to identify and analyze Ponzi games on three public blockchains. Many Ponzi games take the shape of a snowball system that promises high returns and where the early investor's return is financed with the money of late investors. Since every transaction on a blockchain is observable, we can identify the winners and losers and their strategies. The paper sheds light on the nature of Ponzi games that typically take place in obscure corners of the financial system.