Complex sentence: In the 1990s, Fischer patented a modified chess timing system which added a time increment after each move, now a standard practice in top tournament and match play, and created a new variant of chess called Fischer Random Chess or Chess960.
Split into simpler sentences: In the 1990s, Fischer patented a modified chess timing system that added a time increment after each move, now a standard practice in top tournament and match play. He also created a new variant of chess called Fischer Random Chess or Chess960.