It has something do do with the mental state that you are in before you start to play the game. When in gameplay and after gameplay the mental state you were previoulsy in has been altered by the misleading, unclear and unbeleviable ammount of activiety that happend in a short period of time. As a result, confuses you to think "what just happend." although asking your self this question you really dont know the answer untill days, weeks or months from when the game started.
The definition of a mindgame is an exmample of a mindgame.