IN A NOW FAMOUS 1964 article in Ascent magazine, "Games Climbers Play," American climber Lito Tejada-Flores defined climbing as a game, "precisely because there is no necessity to climb." Tejada-Flores outlined a hierarchy of the game consisting of seven basic forms: bouldering, cragging, continuous rock climbing, big-wall/aid climbing, alpine climbing, super-alpine climbing, and expedition climbing. After 41 years of evolution, today we would have to add at least five more—ice climbing, sport climbing, sport ice climbing, gym climbing, and speed climbing. Each of these climbing games has a distinct set of rules.

According to Tejada-Flores, bouldering is the most complex game in the hierarchy, because it has the most rules, or prohibitions—no rope, no rack, no belayer. On the other end of the spectrum, expedition climbing, "although complicated to organize and play, is formalistically speaking, the simplest of all, since virtually nothing is forbidden to the climber. The recent use of aeroplanes and helicopters exemplifies the total lack of rules in the pure expedition-game."

I've always admired Tejada-Flores's explanatory essay, and even more the book of climbing essays it inspired—1978's The Games Climbers Play—but I think Tejada-Flores had his hierarchy upside down. Certainly for most of us, the more players, the more equipment, the more money, the more logistics, and the more risk, the more complicated the game is. Isn't bouldering—which requires a rock, shoes, and a chalk bag—the simplest, even purest, form of climbing? The polar opposite is four unshaven, unwashed guys stormbound for the third day in a two-man tent on a ledge at 26,000 feet, wondering why the hell they didn't take up golf instead.

Still, Tejada-Flores's larger point stands: Climbing, at heart, is a kind of game, even if it is sometimes mortally dangerous. But because climbing can kill you, many people—including me—flinch at the frivolity implied by the word game. Is bull riding a game? Is BASE jumping a game? Perhaps this is elitism, or simply semantics. All these activities have rules, and rules are essentially a code of honor created to protect the spirit of the game. In BASE jumping you must leap from something on earth, rather than from a plane; in bull riding you must hold on, but with only one hand, for eight seconds.

Of course, you can always break the rules. It's your conscience. In the mountains, there are no referees or spectators. The freedom to make your own choices is one of the reasons we climb.

As Tejada-Flores wrote, "Ethical climbing merely means respecting the set of rules of the climbing-game that one is playing."

Which isn't to say that the rules never change. When I started rock-climbing, in the mid-seventies, the sport was in the midst of an environmental and ethical revolution. Pitons—metal nails hammered into the rock—were being replaced by stoppers and hexes, devices that could be placed in cracks and easily removed without scarring the stone. Today, "pins" are used only as a last resort, when none of the less invasive forms of protection will work. The shift from pins to hammerless equipment improved the sustainability of a finite resource—some cracks were becoming nothing more than a series of pin scars—and, consequently, improved the sustainability of the sport itself.

The evolution of rules to preserve the integrity of the game is commonplace. Hunting is a good example. In 1738, to protect its dwindling deer population, the colony of Virginia banned the harvest of does. In 1878, Iowa became the first state to initiate bag limits on game. In 1935, the Migratory Bird Hunting Stamp Act established a law requiring waterfowl hunters to purchase a federal duck stamp; proceeds were used to finance the purchase and management of waterfowl refuges. The list of hunting regulations designed to preserve the resource, and the experience, goes on.

In 2002, nearly 100 of the world's top mountaineers collaborated in drafting the Tyrol Declaration on Best Practice in Mountain Sports. It was distributed to 89 alpine clubs in 67 countries and published in The American Alpine Journal in 2003. If you haven't read it, do. (The text is widely available online.) It's a pivotal manifesto that outlines in plain Strunk-and-White English the accepted rules of the climbing game. It presents a hierarchy of values, with human dignity at the top, followed by life, liberty, and happiness; the intactness of nature; solidarity; self-actualization; truth; excellence; and adventure. There are ten articles in the Tyrol Declaration, each one addressing a different aspect of climbing, from conservation to responsibility, first ascents to sponsorship.

Article 8 is about style. It ends with one far-reaching sentence: "Good style on big mountains implies not using fixed ropes, performance-enhancing drugs, or bottled oxygen."