The Maw is a very short game; downloadable from the Xbox Live arcade, you can get through the entire storyline in about three hours. And this was the one thing that annoyed the otherwise-thrilled critics. I read a couple of dozen write-ups of the game, all of which were highly positive — but which complained that The Maw was “too short.” (See ME Gamers, A.V. Club, Gameplanet, GamePro Arcade, Game Focus, AtomicGamer or Games Radar.)

Granted, The Maw is indeed a wafer-thin repast compared to most games these days. I’m slow, so it took me four hours, but that’s still only one-tenth the traditional “40 hours of play time” that has become the atomic standard in the game industry. Since most new games cost about $60, and The Maw is $10 — about 16.7 percent of that price — you could argue that by math alone The Maw ought to be a few hours longer. (40 hours x 16.7 percent = 6.68 hours, if you want pinwheel-beanie precision.)

Still, the uniform kvetching about The Maw’s short span made me wonder: Why exactly is 40 hours considered the natural length of a videogame? Is The Maw really too short?

Or is it more possible that other games are simply too long?

Forty hours might sound like a reasonable amount of play. But the truth is that very few games offer an experience that truly requires — and rewards — 40 hours of play. After all, one of the chief joys of gameplay (which nongamers tend to misunderstand) isn’t in having mastered it. It’s in the process of mastering it. You start off stumbling around, not really knowing what your goals are, how your enemies and obstacles behave, or the complexities of your weapons and abilities.

Then, largely through a process of head-slapping trial and error, you begin to sense how the system works. If the game is incredibly complicated — like chess — you’ve got years and years of play ahead of you; you may never really apprehend all its nuances.

But most videogames aren’t anywhere near the complexity of chess. Nor need they be: They’re intended as a more-immediate and user-friendly sort of entertainment. Another central pleasure of being a videogame devotee is in constantly sampling new types of play mechanics — like the gravity-bending of Prey, the dimension-flipping of Super Paper Mario or the space-tripping of Portal. It’s like dim sum for the brain: We love being handed a slightly newish (but not completely foreign) treat to puzzle over and test-drive.

But the truth is that most game mechanics simply do not need 40 hours to reach their limits. For example, I loved Fallout 3’s fight mechanics and moody design, and played it for several evenings in a row. But then battles and environments began to feel too similar, and my attention started wandering. Sure, I know there’s another 120 hours of stories and environments to explore. But I don’t care: 10 or 15 hours is more than enough.

In contrast, The Maw felt like the perfect length — because the game ends precisely at the moment that your learning curve flattens out. After three hours, I felt like I’d figured out every permutation of weird trick I could pull with my ever-expanding Maw — so when the ending arrived, my brain felt perfectly exercised.

The Maw’s designers understood that a campaign-style game isn’t merely about keeping players going by offering them more story or more environment. It’s about keeping them going by offering new wrinkles in the play. If designers run out of play before they run out of story, the game dies.

The truth is, tons of very good, very enjoyable narrative games have only about four or five hours of really serious play in them. They probably shouldn’t drag on for 36 more hours. There’s even a practical benefit to being shorter: A four-hour game appeals to a much larger pool of gamers — including the many adults out there who want to experience the delicious sense of closure you get from completing a narrative game, but who simply haven’t got the time (as I argued in my previous piece on “The Mythical 40-Hour Gamer”).

Now, there are some obvious practical pressures on game designers to keep things long and drawn-out. Really complex modern games cost a lot of money to make, so you probably need to sell them for $60 — gamers likely won’t pay that much for a few hours of play. The market pushes designers into the temporal equivalent of bloatware. (Bloat-time?) It would be wonderful, of course, if every game hit a golden mean — with play mechanics that simultaneously reward a couple of hours of play, yet also deepen and enrich after literally months of play. (Many argue this is precisely how a good online game functions, be it World of Warcraft or Halo, or a super-addictive casual game like the new — and derangedly awesome! — Drop7.)

But for my money, I’d love to see more designers aim for The Maw’s mix of brevity and innovation.