You might as well have set something up because you are going to have to do something really well in order to surprise someone. Or you can just watch a game with the person you like and see for yourself if a game is well played. There are so many reasons to say it and you just have to find the right moment to use it.
For example, you can be having a game of Tetris in a social media site only to realize that you have lost against a fellow player. Now, what best way to congratulate your opponent by sending him or her a chat that tells him or her how well played it was and how you are honored having have to play with him or her.
On that note, here are some well played meme that you can use any time that you want to say that.