I think there's a clue with the 13 chapters thing, the name of the game itself is the 13th instalment so the amount of chapters fits

i know that doesn't give it the right to be watered down (just so the name and chapters matches, its just something i though of)
Also i think the ability to play the game even after you have completed it adds on more hours, i saw someone with 115 hours of game play on it just in the chapter when your in Hopes house...