Recently it was revealed by Game Informer that Metal Gear Solid V: Ground Zeroes' s main mission is less than two hours long. In response, Hideo Kojima released an official statement to his Twitter fans that delves into the game's length and how it'll enhance the experience:

In other words, Kojima feels that Ground Zeroes is very non-linear--unlike past titles in the series--and that the main mission coupled with the five side missions, along with the Trial Records and Play Time features, will increase the re-playability of the game. Personally I'm not upset with the length of the game itself, but I find the pricing of this game a little too much.