CryptoNinja is a strategic game based on a blockchain platform and main processes are fully coded by smart contracts. In this game, players can play this game in two ways. One is setting a reward to the castle, setting up a trap and waiting for a ninja. if another player’s ninja fail to sneak the player will get one-half of the reward. The other is, choosing another player’s opened castle and one of owned ninjas and sneak the castle. The trap affect the ninja’s HP decreased. If the ninja succeed the player will get rewards and if failed has to pay half of the reward. After the sneaking, traps that the ninja passed through are released. Players can see the information and choose the castle to sneak, so the probability of success will increases later and later.