In Fallout there are no rules. They prefer that you do the story but you can go off and build a house or kill a person that is going to give you a thousand dollars. This exercise is difficult because I don't normal play games that has no rules and I play games that have objectives and you are strictly to do what the designers made the game for.
Three games that are difficult is Flappy bird, Guitar hero and Mortal Kombat because I don't have good timing to hit the buttons and the screen at the correct time.
The premises for the games Clue and Guitar Hero. Clue is to find the killer and what they used to kill the person and Guitar Hero is to get the highest score. The premise of Call Of Duty is to kill the opponent and to get points to win the game. The premise of Forza Motorsports is to get first place and to upgrade your car.