Of course, this means that players will sometimes surprise game designers by doing things even they never thought of. This spring, executive producer Jonty Barnes watched a tester run around in a multiplayer level of Halo 3 that's constructed like a deep canyon. A bunch of Gravity Lifts were scattered around the bottom, and the player was bouncing from one to another. Then the tester got a clever idea: He grabbed one lift and, holding it, jumped into another one, launching himself up onto a high ledge. He then placed the second lift on the ledge and used it to bounce up even higher, landing on the top rim of the canyon. That area wasn't even supposed to be accessible to players.
"So he's up running on the canyon ledge, and the engineers are going, 'Christ, how the hell did that happen? Do you know what kind of bugs this is going to cause?'" Barnes laughs, a hint of pride in his voice. "But that's what you get when you set people free in your world."
Halo 3 is a vibrant, beautiful game, but it's also a bit cartoony. It doesn't have the eye-popping verisimilitude of, say, Gears of War, a rival Xbox 360 hit from Epic Games that dazzled fans last winter. Many critics have made this same comparison, and it's a sore point among some Bungie designers. They like to note that Gears of War — like most of today's shooters — takes place mostly in narrow corridors with only a few enemies at a time, so its makers can lavish attention on every square foot of space. Halo 3 is set in sprawling outdoor levels, with dozens of alien enemies swarming onscreen at once. The vastness of the game's geography means that gamers can replay each battle several times, trying several radically different ways to fight through it. It also means that Bungie's designers have to spread the Xbox 360's processing power around more thinly.
But though expansive levels may be one of the keys to Halo's appeal, the problems they cause go well beyond graphics. Enormous battlefields also create lots of places where things can go wrong — areas where players can get bored, stuck, or killed. This has been one of the main challenges facing Halo 3's designers; it first showed up in testing of the beginning Jungle level. Players were simply baffled about where to go.
In the lab, Pagulayan pulls up an early map of Jungle; on it are superimposed the locations of about 30 testers after half an hour of play. The dots are scattered throughout the terrain. This, he says, is bad: It means that people were wandering aimlessly instead of progressing through the level. "People were lost," Pagulayan says. "There wasn't much deep analysis to do here."
To solve such problems, the designers must subtly direct player movement by altering the world in small ways. In this case, they decided to change the geography of the Jungle level so that in certain places players had to jump down a steep ledge to reach the next area. This way people can't go backward, because they can't climb back up the ledges. Pagulayan shows me a map from the next testing round, after the fix was implemented — and sure enough, all the dots are clustered in tight bunches, right where they are supposed to be.