With this option activated Rebel will think his opponent is a GM (grandmaster) and will play differently. Rebel will try to be more humanlike and accordingly will play with more risks. This option was first activated during the match against Anand in 1998 where Rebel scored 5 out of 8 games! Without this option, we believe Rebel's score would have been lower. You'll have 4 levels of anti-GM software to choose: none, active, strong and smart.