See as I am pretty confused as to whether or not you want your child to play Assassin's Creed, I am taking it you don't want him to. So I will begin by stating that it really depends on your child's state of mind and maturity. If he has temper tantrums, is easily angered, I wouldn't recommend you let him play the game. However if he understands that it is just a game, and is playing rather for just his own enjoyment, he could learn a thing or two about certain aspects in history that the game implements. Although I did play the game at around his age, I was able to understand its depth in meaning, problem solving, and appreciated its level in graphics and story. However the violence and mature language can have a negative impact if your child is still at the age of learning from adult behavior. It is possible he learns adult language and there could be a chance he results to aggressiveness during real life situations that are similar to situations in the game. There are both pros and cons to letting him play, but it really depends on your child. If you are still worried, I would recommend you sit next to help and guide him if he needs help. And yes, it can be frustrating for adults as well.