You're a gamer, so I'll put it like this. American football is like a turn based strategy game, like those crappy old final fantasy games or dungeons and dragons. A player chooses their attack, their opponent chooses a defense, the move is executed, a dice is rolled or a computer crunches some numbers, and the efficacy of the play is determined. Then they spend 5 minutes setting up again for another 20 seconds of gameplay.
A sport like Australian rules football, or rugby league or rugby union, is more like a multiplayer team based game, like COD or BF or titanfall (I admit I don't know if titanfall is team based, I just put it in because you play it). The point is, everything is fluid. Any player can make any move at any time, and everyone has to think on their feet, and you don't get to stand around and have a chat about it for most of the game.
I saw a stat not so long ago that the average game of American football has about 11 minutes of actual gameplay. In our football the only break is halftime.