Ethereum crypto-games are a booming and relatively unexplored area of the games industry. While there is no consensus definition yet, 'crypto-games' commonly denotes games that store tokens, e.g. in-game items, on a distributed ledger atop a cryptocurrency network. This enables the trading of game items for cryptocurrency, which can then be exchanged for regular currency. Together with their chance-based mechanics, this makes crypto-games part of the recent convergence of digital gaming and gambling. In a first effort to scope the field, this paper surveys popular crypto-games, which use the Ethereum cryptocurrency, to tease out characteristic technical properties and gameplay. It then compares the games' features with criteria found in current legal and psychological definitions of gambling. We find that the popular crypto-games selected meet a combined legal and psychological definition of gambling, and conclude with ramifications for future research.