Thanks for all the replies.
I dont really know enough about it to be honest so i have to take it as read what Ashley says. What does seem strange is that the closure compiler doesnt give any errors. The output just doesnt run. If i check the running processes then my game is running but there is nothing on the screen. I have also tried it on another machine, just the same.
I have to assume its something in my C2 project that it doesnt like although you would imagine it wouldnt run minified or not.