Never Scored a Point with That Fat Head....
Don't listen to anybody commenting how you can't devise something, even something that's fundamentally flawed or mediocre, based upon a silly in-joke or involvement from relatives. That's just missing the point entirely.
The major issue here is that, from a few minutes of play, I was in a constant stalemate with the computer. It tracked the head with such flawless, precise effort that it was impossible to get a shot past it. Eventually, I just quit, zero points on both sides.
While Pong has been done to death, it has been done differently each time. This one's challenge rating is exorbitant, utterly ridiculous. The only good part about your in-law's fat mug is that it's a nice, wide target, which eases your ability to smack him back to the opponent but only makes it harder to get past the opponent!
In all, it is a grossly flawed game. That's why I gave it the zero. How you conjured up the idea behind the game is your business; you may even want to pursue more cooperation from relatives and friends in your Flash endeavors. Just keep in mind that if you're going to create a game, you ought to give it a beta phase where people can test whether or not it works, or if it can be beat.