It may depend upon how old your son is and how serious the football is. If we are talking 8 year olds, how serious is the game at that age? Will his team mates feel let down, or will they just play happily along without him?
I think the way for you to think about this is to think about what is best for your son. If he is young, I personally don't think having him miss the game is going to corrupt him for life and turn him into someone who blows off his committments. On the other hand, what good will come to your son going deer hunting with his dad for the first time? I hope you are healthy and live forever, but what if you get struck by a bus and killed next March and your son never gets to deer hunt with you? On the otherhand, if he is a sophmore in High School, maybe the the lesson about making and keeping committments is more important at that age. But base your decision on what is best for your son.
Let's say your son decides to play the football game, I don't see that it is critical that you attend the game. I'm assuming you probably attend all the other games, or a good share of them. In this circumstance wouldn't your son understand your missing the game? Particularly if we are not talking about the state championship football match. In general I think it is important to encourage and support your children in sports and other growth activities, but I don't think this necessitates 100% attendance at their games.
These are just my opinions. I've been wrong before and will be wrong again.