If a new user opens our app-center-page via "App-Center" -> "Games" -> Family -> "HorseHaven" and clicks on "Play Game" nothing happens. In that case the button acts as a submit-button for a form with action "http://www.facebook.com/connect/uiserver.php".
For an existing user the button is an <a> tag with the correct href to our game.
Steps to Reproduce:
Go to "App-Center" -> "Games" -> Family -> "HorseHaven" and click on "Play Game"
User is redirected to the game
1 person can reproduce this issue by following these steps