What does a computer opponent have to do before a player stops thinking of it as software? A studio building card opponents for a commercial title is solving a design problem dressed up as a technical one, and the technical part was finished by researchers who were never trying to make anything fun. Rules Borrowed From the TableStudios rarely design a card opponent from scratch, because the ruleset arrives with decades of documented strategy attached. Search Under Hidden InformationThe standard technique for a computer opponent that has to plan is tree search. Human Timing and Deliberate ErrorThe tell that gives away most computer opponents is the clock.