Pain Point Introduction
Some games have been played against a remote opponent for a long time. Chess by mail has a history spanning many decades. A game like poker, however, characteristically involves placing significant amounts of money at stake and suffers from a need for trustworthiness after the game. How do you prevent the losing player from claiming that less money was in the pot? Block Chain can be the answer.
Source: https://www.888poker.com/poker-promotions/
Concept
A poker game is played among peers. There is no player with a permanent supervisory position like the bank in roulette. How much money is at stake is made clear by putting it into the middle of the table, where every player can see it.
Which player played which card in which order is recorded in the same way. The winner is determined by making cards public and common rules which allow objective ranking.
Record keeping
A poker game, or any card game for that matter, can be seen as a sequence of actions, like cards being dealt, cards being played, money being placed in the pot, players folding and so on. From a complete record of these activities games can be reconstructed and there is no doubt about who won how much money.
Cheating at the game would require the cheating player to alter that record. That is exactly what a classic Blockchain is designed to prevent generating random cards.
Card games need to deal with cards being dealt. These cards should be random and they must remain unknown to the player who got them. At the same time the dealer must not be able to manipulate who got which cards. This is also possible by block chains and cryptographic hashes. The sequence of cards in a deck can be uniquely represented by a number.
Generating polynomes for pseudo-random sequences are known to literature. If the seed value is known the sequence can be regenerated deterministically. Hence each player but the dealer generates a random number and stores it in the block chain so that it is known only to a subset of players different for each random number. The dealer makes a seed value and uses the stream of random numbers to answer each request for revealing a hidden card. After the conclusion of the game, the random values can be revealed and the sequence be recomputed. The dealer cannot cheat without being detected and the use of a cryptographic hash prevents manipulations from the other players.
Business reasons
The algorithm described so far can be used to play any card game with a blockchain. The manufacturer of the game can sell it and need not provide any further infrastructure to the players, thus reducing running expenses to zero.
Money can be made selling software and providing a platform for matching players, which can do advertisments, but is freed from the costs of actually running the game.