Ethbet is a decentralized, peer-to-peer, and provably-fair Ethereum-based dicing game without a mandatory house edge. Ethbet is able to offer bets without a house edge because players bet directly against other players instead of against a centralized house. The disadvantage of this is that in order to place a bet, there must be another party willing to place the same bet. For this reason it is possible that a player must wait for their desired bet to take place, especially if it is very large. To combat this, an additional feature of an optional player-defined house edge is added, allowing players to offer and take (‘call’) bets with any house edge that they desire. Thus, a player that prioritizes speed over their expected return can agree to a bet that gives him a slight disadvantage (i.e., a bet that gives his opponent a small house edge). Similarly, a player that is patient and prioritizes their expected return can offer bets that the formerly mentioned player may choose to call. This results in a model where players are effectively able to become their own casinos, allowing market forces to provide players with bets as quickly as possible at the best possible rates. The Ethbet protocol features an efficient off-chain matchmaking relay in order to allow players to quickly and cheaply communicate their intent. The protocol can also be extended to support betting using any Ethereum-based (ERC20) token and for use with other games.