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 Fischerandom (Chess960).
Split into simpler sentences: 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. He also created a new variant of chess, called Fischerandom (Chess960).