Just install an ad blocker extension.
I see where you are going, but I think it needs some tweaking. Here's my suggestions: first, I think you should display current score to the player as a motivation to keep going. Second, I believe you can make the difficulty increase gradually by making the [X] buttons bigger initially and making them smaller as the time goes. Also, you could make ad appear frequency increase gradually as well.
Nonetheless, nice job!
P. S. Why is it loading one of my CPU cores to 100%?