Home field advantage could be added pretty easily by using a system similar to what NCAA used to do, Have Pre-Snap PlayArt and Receiver Icons distorted/removed in relation to the crowd noise, also when the crowd gets really rambunctious you could have the offensive team's controller vibrate like mad. This would be cool for 3rd and short situations. Also, I saw they are improving the penalties this season to include more false starts and procedural penalties in clutch situations. Just an idea.