You do not need a third-party app or anything like that to unhide the game; all you need to do is fire-up a command, and it will activate the game for you.
1. Launch a conversation with a friend you would like to play the game with.
2. When the conversation panel opens, send them a message that says “@fbchess play” (without quotes), and the game of chess will begin.
3. As soon as you send the above message to your friend, the conversation window will immediately show you the chess board to play the game.
Similarly, you can move the other pieces you wish by using the first letter of the piece’s name and the location of the tile you want to move them to.
If you would like to maximize the chess board, then you can do so by clicking on the Settings icon in the chat window and selecting the “See Full Conversation” option. That should help you get a little larger view of the game.
If things are not working well and you wish to offer a draw, you can do so by sending in the command “@fbchess draw offer” and the opponent will receive your request. Lastly, if you do not want to play the game anymore and wish to resign, then send in the command “@fbchess resign.”