bots are more difficult in poker because there is a bigger randomness factor with what cards can fall and the actions to each situation. Chess bots have only to know the basic principles, opening strategies and the like. For instance, knowing that controlling the center of the board above all else is easy enough to program, but how do you program a computer to make the best possible move in poker knowing that any number of random cards can fall on 3 different streets. In poker, you would just have to program it to make the "mathematically correct" decisions solely based on odds.