How do chess games have coded different level of difficulties. Do they have different efficiency of programs or what?

Question

Please explain for other games too if possible.

In: Technology

Answer 1

Sometimes, particularly in the opening book phase of the game. Most of the time, the chess difficulty is controlled by varying the size of the move search tree considered by the algorithm. In easy mode it might look at all its moves and all of your moves, a search depth of 2 plys. In medium mode it might look 5-6 plys deep in the best half of the moves. In expert mode it might look 8-10 plys deep at all of the moves.