brain games

What is the absolute best game for taxing the brain in the large -file games?

HI MIGGYDO,
WELL AS YOU SEE YOU'VE PUT EVERYONE IN SHOCK, AS YOU MAY KNOW BY NOW, NO BODY "EVER" ASK "WHAT TAXES THE BRAIN AND LARGE FILE" IN GENERAL, MUCH LESS IN THE SAME QUESTION.
HOPE YOU FOUND YOUR ANSWER HON, WELCOME TO THE POND.