There are metallic hummingbirds spitting through the leaves just over our heads. Small arms fire, popping and buzzing, echoes through the lower valley. The guy watching my back looks over at me and indicates with sign language - two fingers to his eyes and an arch of his hand - that two shooters perch in a stand of trees just over the knoll.

I'm experiencing first-hand what it feels like to be hunted. And to hunt. Beyond the field of vision, our enemies have no face - they are covered by black mesh masks. They hide in the trees after sneaking carefully along a septic trench on the outskirts of the field.

"Go, go,'' he whispers. I crawl on forearms and elbows, dragging myself to a clearing. "We're killing people, and people are trying to kill me,'' I mutter. I make a break for it, jumping over a trench into a bunker, swallowing the metallic taste in my mouth.

Fllip! fllip! flip! flip! flip! - hundreds of hard plastic pellets a second, from four or five angles, slam into the tires above my head.

I'm in Yuen Long. This is just a game of war. A game.

"Never give away your position,'' Ian Scott, an expatriate consultant on the Disneyland project, has warned me. "Where are they?'' There and not there. Invisible but for the sound of their weapons. I grip my MP5 machine gun and jump up over the crest of the clay hill to confront my attacker. It's a woman with long black hair.

I let loose a stream of 6mm BBs into her neck. Her eyes widen behind her mask. Then someone - her boyfriend - rakes my chest with submachine gun fire. "Sai ah!'' I yell, in keeping with the rules of engagement. "I'm dead!''

As we walk off the battlefield, Joseph Castillo, one of my squad members, whispers: "Is that the girl you shot? The marks on her neck look like love bites.''

A day after the 30th anniversary of the fall of Saigon, I'm playing war on a muggy day at the Tai Tong War Game Service Center, outside Yuen Long Town in the New Territories.

This is not Paint Ball, but something else, a little more real, a little more painful.

AirSoft war games, a simulation exercise where people shoot each other with shot powerful enough to break the skin. It has a large following.

I spent Sunday with "the Lurps'' - a team of Filipino landscape architects and a couple of their buddies.

On any given weekend, hundreds of camouflage-clad players line Wong Wah Street in Yau Ma Tei, long, flat, black bags on their shoulders. They wait for buses to take them to a few popular war game centers around Kowloon. The sight of men dressed up in full battle gear is a bit disconcerting. In each of their black bags are replica weapons.

The most prominent of these game sites is CombatGames in Sai Kung Country Park. It's owned and operated by a few retired Special Forces soldiers. But those diehard war-gamers call the battle off for rain, making me wonder how tough they can be. So I teamed up with Edwin Galicia, a CAD designer from Manila, to play in Yuen Long. Galicia, a tall and baby-faced man smiles easily and plays twice a month with his team of "militarist collectors'' and part-time AirSoft enthusiasts. They take their name from the Long Range Reconaissance Patrols (nicknamed Lurps) of the US 1st Infantry Division who served during the Vietnam War.

Kitted out in flak vests, goggles, helmets, camo, gloves, ammo packs and combat boots, the teams play several games during a typical eight-hour day. They hide in thick forests or engage in Close Quarters Battle (CQB) in mock setups for "urban warfare'' or "field and stream.'' They also play, at other AirSoft sites, "Sniper'' and "Shoot the President.''

In a game like CQB at this site in Yuen Long, dozens of players charge towards each other at the end of a three-second countdown, thousands of BBs sizzling through the air. "Soldiers'' hide behind barrels, or in shot-up Hong Kong police vans with broken windows and scattered glass chips. They wait and shoot, hugging cover, coldly eyeing each across the battlefield with a stoic and practiced brutality. The BBs are hard - and fast enough to break the skin - as John Delprick, a design consultant for the hotels at Disneyland, can attest.

"Ah, it's nothing, my skin just breaks easily,'' he laughs looking at three bloody welts. It's his first time, and he's loving it. "In my day job, I can't get rid of my aggression,'' he says. "You know what frustration is, don't you?

"It's the right to kick the living s*** out of some poor son of a bitch that deserves it.''

He laughs. Delprick seems like the kind of guy built for this game. Long, gangly, smokes a cigarette. Tells jokes. Has a brain that's always thinking strategy.

First-hand experience shows me this game is all about power and control, mastery of a moment in a competition for success.

When the whistle blows, adrenalin mixes with fear and anticipation. We want to win.

"These guys don't go down when you kill 'em,'' mutters Scott, as he positions himself behind a smashed up Mercedes.

"This thing's like artillery,'' he complains of his replacement M-16. The US infantry weapon is not comparable to his beloved AK-47. He left that in a closet after it stopped firing accurately.

Then, out of nowhere, a shooter plugs him through the heart. He's dead. He drops back in frustration. No complaints. These are the facts of war. Things don't work. People die.

The philosophical lull is broken by the sight of men running from the center of an urban battlefield - police vans and rusted Subarus. They weave in and out of a maze of canvas walls to our left.

"You need to watch the angles,'' shouts Scott.

I slip into the maze. In three seconds, I can hear the breathing of my opponent through the thin canvas skin that separates us. He could lunge through at any second. My teammates Rommel San Diego, Galicia and Castillo come up behind me. Galicia jumps around the corner.

"He's right there,'' I tell him.

"Bingo,'' says Galicia, but the enemy won't concede. His gun has jammed. Galicia isn't going to shoot him at such close range, figuring he has him there.

I lower my gun. I see his shadow on the walls. The enemy pulls out a pistol and shoots Galicia in the face and neck.

Primal instinct takes over. In a split second the enemy looms around the corner and I don't even think. Screaming, I shoot him in the groin, from only a metre away, his eyes grow wide as he brings his pistol to my face. I don't know who - San Diego, I think - shoots him and he finally gives up.

Later, at the mess tent, we talk about why people do it. Why play at killing people?

"It's just this primordial instinct, you know?" says Delprick. He inhales his cigarette and blows it out, his battered cheeks sinking in.

"I think of my boy with one of these guns,'' he says. He's out there playing around, Delprick says, miming the action of a man with a gun. He cracks a big laugh. "You're the hunter, you know?''

"It's hard, when you're in a territory you're unfamiliar with, and you don't know all the guys you're playing with,'' says San Diego. "You can't just joke around.''

Even more, though, it's all about honesty and sincerity, say some of the guys. There was a big problem today with players who wouldn't die when they got shot. "There is no distinct line for when you are hit and you die," San Diego says. "It's all about a person's honesty."

His comments remind me that for this fraternity this is a serious game. It recreates, in a way, the fear we have of death and the intense relationships that danger evokes.

In real life, of course, the bullet that splits your skull countenances no such ponderings.

But for us, it is a game. Sweat moves down Galicia's temples and soaks through a scarf he knots around his neck. He looks at me, and then off into the distance. "Some people will hide,'' he says. "Just like in the movies. They will survive, for sure. But what's the fun in that?''