While an alright version of Mahjong, the game breaks itself by having almost no actual difficulty. Players have unlimited use of the shuffle button, and in many cases it's simply easier to shuffle the board then to try and look for that last pair to eliminate. In addition using the shuffle button does nothing to add time to your clock, so it's almost encouraged to spam it if you wish to get a decent time.
Also, the fact that the shuffle can result in zero matches is just lazy programming. A subroutine could easily be put together to make a shuffle only valid if it has 1 or more matches.
For a game that already has so many versions out on the web, this really needed a lot more polish and care for it to stand among them. Remember to do a little research and get a good grasp on what people like about a particular game or genre, and be sure to either do it better, or bring something new to the table to make it unique.