Smart contracts in Ethereum allow anyone to verify its source code. This enables smart contract gambles, where any participant can be certain, that the bank is in fact not cheating on you. If we want to play high-stakes games, there is a potential risk though. The problem The miner incentive to cheat becomes a serious threat, because we might a rely on the block hash for our random number generation. Playing high-stakes implies an increased chance for the current block reward to be lower than the expected gain from the gamble. This encourages a miner to cheat by not publishing a newly found block if its block hash implies loosing the gamble.