Somebody uses "two hours" and "complete game" in a sentence and it's all over: the echo chamber engages missile lock and there's blood on the street, mass hysteria and drive-by commentary that'd make a sailor blush.
So let's all count backwards from five, and when it comes to Konami's forthcoming Metal Gear Solid aperitif, not assume that the two hours some critic says it took to muscle through a prerelease version of the game is going to be our two hours, anymore than my time playing Flower is going equal yours nudging an entourage of skittering flower petals around bucolic vistas.
I have no idea how much play time I'll get out of the game's primary mission (and five side ones). Neither do you. The fellow at Game Informer who previewed it does, but only in the sense that he probably played through the main mission without dallying. I don't know about you, but in sandbox-style games, I dally. I goof around and string things out. I admire the scenery and sound design and poke the game -- and die/fail often -- to see what it'll do.
Is MGS: Ground Zeroes that sort of game? Creative lead Hideo Kojima says so, distinguishing between "play time" and "clear time." Critics routinely conflate the two.
Remember, as well, that we're talking $20 for the digital version on PlayStation 3 and Xbox 360, and $10 more for a digital copy on PlayStation 4 and Xbox One. That's not as cheap as, say, games like Journey or Flower, and we can certainly have a debate about the price ($15 or $20 for all versions might've been wiser from a PR standpoint). But the measure of a game can't be taken from its clear time if it's well-designed and interesting enough to encourage broader, more thoughtful engagement (whether MGS: Ground Zeroes falls into the latter category is another matter).
In other words, if your whole philosophy of gaming involves punching through gameplay choke points, quick as can be, then your problem isn't Metal Gear Solid: Ground Zeroes.
Besides, you can finish Bethesda's opus gigantus, Skyrim, in just two hours and 16 minutes if you really, really want to (and no, I'm not making that up).