Confusion was caused earlier when a N4G news article said 'MGS4 Rated, total running time reveled'
"The information you have gotten comes from the BBFC, which decides a game's rating. They don't play through an entire game and decide the rating, they are given pieces of content. The whole explanation is boring, so just look at these links from the BBFC.
Click the MGS4 link and you'll see where that site got its "scoop" about MGS4 only being 9 hours long. It has nothing to do with the actual length of the game, unless MGS2 is 8 minutes and MGS3 is only 3 hours. It also is not necessarily the cutscene length, or gameplay length. It doesn't work that way."
This confirms that the total running time doesn't mean the actual game length.