Right answer: Sabes jugar muy bien.
If you want to congratulate a friend for his or her performance in a game, you would fisrstly talk to him or her using the 2nd person in singular (informal) you, and then express how good that person played.
It would be something like:
You know how to play very well
Which in Spanish is:
Tú sabes jugar muy bien
Nevertheless, it is important to note that in Spanish is not always necessary that the subject is explicitly in the sentence, it is called Tacit Subject, Implicit Subject or Null Subject.
This is because the subject is encoded in the verb conjugation. So, another good option is:
Sabes jugar muy bien
