I guess it all depends on the closeness of your high school chums - we've had a 5, 10, 20 and 25 year reunions, all situated around our high school football games. I was able to be present for the 20 year reunion, and we had a tailgate party at the school/football field, where we had friends from other 'classes' stop by and and have a hotdog with us. It didn't matter to us that they weren't from our class - they were friends, so they got a dog.
Did we all sit and watch the game? No, because only one of us had a child in the game. Of course, the coach was a friend of my older brother, so it could have meant more, I suppose.
But the big thing was that we could all get together and see what all we'd made of ourselves. No one cared how much weight we'd all gained, or how much hair we'd lost. We were together again, and that was what was special.
Oh, the joy of being from a small town.....