The first Advanced Chess event, in which each human player used a computer chess program to help him explore the possible results of candidate moves, was held in June 1998 in León, Spain. The match was played between Garry Kasparov, using the German chess program Fritz 5, and Veselin Topalov, using ChessBase 7.0. The analytical engines used, such as Fritz, HIARCS and Junior, were integrated into these two programs, and could have been called at a click of the mouse. It was a 6-game match, and it was arranged in advance that the players would consult the built-in million games databases only for the 3rd and 4th game, and would only use analytical engines without consulting the databases for the remaining games. The time available to each player during the games was 60 minutes. The match ended in a 3-3 tie.
Since the first event Advanced Chess matches were often called Freestyle chess, in which players can play without computer assistance, or can simply follow the directions of a computer program, or can play as a "centaur", listening to the moves advocated by the AI but occasionally overriding them. In 2014 the best Freestyle chess player was Intagrand, a team of humans and several different chess programs.