Ground Zeroes, the next installment of the Metal Gear Solid saga, probably shouldn't be treated as an "installment" if you can complete the main mission in a couple short hours.
Ever since the dual announcement of the two upcoming Metal Gear Solid titles, Ground Zeroes and The Phantom Pain, it's become very apparent that Phantom Pain is the one we're supposed to be excited for. Series creator Hideo Kojima already admitted that Ground Zeroes is essentially the tutorial for Phantom Pain, but a recent report from Game Informer suggests that he really wasn't kidding. According to the magazine's preview, the main story of Ground Zeroes can be completed in just two hours.
This claim lends some believability to Kojima's previous statement that Metal Gear Solid V: The Phantom Pain would be "hundreds of times larger" than Ground Zeroes. Granted, that two hour report only covers the game's main story mission, not side quests or exploration, but Metal Gear Solid has never really had much content in those categories. If anything, the game's biggest attraction is arguably its story, which is infamous for extremely long, non-interactive cutscenes. So how much actual gameplay can be in those two hours?
Kojima has said that Ground Zeroes would ideally be part of Metal Gear Solid V: The Phantom Pain, but it's being released early (March 18) to give fans a taste of what's coming up. Of course, that two-hour taste isn't exactly a free sample - Ground Zeroes will cost $20 on last-gen consoles and $30 on current-gen for the digital version, with another ten dollars on top of that if you prefer the physical copy.