If on the last play of a game the offence kicks and makes a game winning FG but the offence is offside the defence should have two choices if I'm not mistaken
1. Decline the penalty and let the points stand
2. Accept the penalty and reattempt the FG
This happened in a sim last night. The FG was not counted and the sim went immediately to overtime.
http://mfn30.myfootballnow.com/watch/1064#189878
If I have the rule wrong please let me know.