I just lost a game where I made a 40 yard field goal as time expired to win the game except there was an offensive holding call. Instead of having me re-kick the FG from 10 yards farther back, the game just ended.

Is this really the way it works? I don't get to re-kick if the defense accepts the penalty?

In the NFL if an offensive penalty is committed at the end of the game and the defense accepts, the play does not count and the game is officially over.

If the defense commits the penalty, the offense gets one untimed play.

... if they choose to accept the penalty (which of course they would if they were losing and down by 8 or less).

Even if the game isn't over, there is a 10 second run off at the end so if u have like 8 seconds left and false start, game over unless the defense accepts

The game cannot end on a defensive penalty, but can end on a offensive penalty even if the defense accepts
http://www.nfl.com/rulebook/foulonlastplay

this just happened in MFN 19

play = https://mfn19.myfootballnow.com/gamecenter/view/3607#711361

Chicago and Green Bay

Chicago was on offense
Green Bay was on defense

thread about it = https://mfn19.myfootballnow.com/forums/thread/1/936?page=1&x=UsEp6TRA80#3890