Counter-Strike: Source

Say goodbye to your sleep patterns. Stock up on fizzy caffeine and teabags. Invest in a freezer and low maintenance, high calorie food. Take a week off work. Kiss your loved ones goodbye. Lock the doors and close your curtains. You need the time, the space and the supplies for one reason: Counter-Strike: Source is here and yes, it's everything we hoped for. Make preparations now. This is going to dominate your free playtime in exactly the same way the original mod sucked away entire days.

To bring you up to speed, Counter-Strike: Source is a direct translation of an ageing, yet brilliant, five-year old, Half-Life, teamplay mod.

Teams of terrorists and counter-terrorists (CTs) face off across exotic, yet realistic terrains. Killing the opposition, planting bombs and winning rounds nets cold, hard currency, which is spent on new equipment. A new rifle, a sub-machinegun, maybe a Kevlar vest and matching helmet. Take down one of the team, and you're left to sit the round out, an invisible spectator.

It's a formula that works. There's a delicious rhythm to Counter-Strike: rushing to choke points, furious exchanges of gunfire, followed by nervous creeping as the remaining players mop up, or move to the objective. CS: Source doesn't mess with any of that - it just paints the stunning Half-Life 2 physics technology over the top.

An example: you're playing as a terrorist, crawling slowly through the tunnel, well aware that ahead, you're going to enter the CT's line of sight. Behind you, a team-mate clips a free-standing tyre, sending it trundling past you, like something from Wacky Races. The CTs ahead are obviously on hair trigger alert too - a burst of gunfire is heard, and the hapless tyre hurtles back towards you. Confirmation that somewhere in the darkness, there's an M1A1 gunner waiting to play. You're trapped.

The new physics effects are striking. Where previously objects within the gamer were static, now barrels and crates can be knocked around the level to create temporary cover, or just to coo over. No two rounds of Counter-Strike ever play the same, thanks to the players exploring their own ideas on how to exploit the enclosed spaces. Now, the very scenery adds further possibilities. Broken bottle shards, empty milk crates, tubs of paint and rusting car parts all react perfectly to your actions. Shoot them, and they'll shatter, skidding across the ground. Lob a grenade instead and they'll be flung into the air, bouncing off walls, clobbering any players they come into contact with. Set off a C4 detpack in a pile of debris and shrapnel will ricochet off everything: tardy terrorists now have to escape, not only the blast radius, but any objects shot across the level. If they clip a player, they will hurt.

It leads to some eerie, shared moments. In the middle of a firefight, a corpse might fly overhead, arms flailing in the air. Both you and your opponent pause firing for a brief second, watching it arc and crumple in the sky, before shaking your heads and resuming hostilities.

There are already some exploits: we've spotted thoughtful players stacking debris on explosives, forcing the CTs to scrabble around, clearing a space before starting to defuse.

Catching discarded weapons in mid-air is another staggering trick. Expect more as pro-gamers settle down with the new code, searching for an advantage.

Along with the improved physics, Valve have given Dust a striking graphical makeover. The grainy, pixellated textures have been abandoned in favour of higher resolution, bump-mapped beauties. Some have pointed out that Dust isn't the best map to show off the spangly new Half-Life 2 graphics engine - all dull beige and brown. But there's a subtlety to the upgrade. There is now a gloriously decorated dome where a claustrophobic tunnel once stood. Sunbeams stream in from tiny portals overhead, illuminating the dust clouds. A few licks of peeling paint here, a detailed backdrop there - it adds up. What was once an anonymous collection of corridors and cubbyholes has been transformed into an abandoned place. This feels real. It bodes well for what is to come.

And it feels vicious. Counter-Strike has always been a fast game, single bullets to the head inflicting instant kills. But thanks to the physics effects, every shot carries weight. Squads are scattered by grenades, bullets ping off walls.

The sound effects are glorious - when the gunfire is muffled, you'll hear the rounds kicking up dirt and ricocheting off walls, all in 5.1 surround. Standing your ground in the face of such assaults can be terrifying: your own Black Hawk Down moment.

That's why we've fallen in love with CS: Source - it's not just about the technology. It's about applying the Half-Life 2 technology standard to a multiplayer game. And it's stealing our lives all over again.

Counter-Strike: Source is available now via Valve's