Crank the difficulty on Left 4 Dead up to Expert and it suddenly becomes a bloody tough game.
The ease with which you romp through default difficulty in little more than an elaborate shooting gallery is suddenly replaced by panicky tactics, lots of shouting and acts of cowardice.
So how do you get through Expert campaigns in one piece? And what is the best way of dealing with those damn Tanks? This guide should help put you on the right path...
Stick Together
The most obvious bit of advice but no less important because of it, it is vital everyone sticks together. The reason for this is because of the special infected - if you get pinned down by a Hunter or caught by a Smoker, you need someone nearby to help you.
The best 'formation' is to have someone slightly ahead of the group and someone who checks for ambushes from behind the group. It's also good to have a mix of shotguns and automatic weapons while you'll almost always want at least one pipe-bomb in the group. If someone does die, remember you can loot his body for unused med-packs and take his weapon too.
Fire In The Hole
Save your pipe-bombs! They are the most valuable weapon. When thrown, all nearby zombies are attracted towards the beeping noise. This is crucial if you need to save an injured team-mate or you're covered in Boomer vomit, so save them for these moments!
Pistol
For those rocking the assault rifle or uzi, it's vital you use the pistol to deal with lone zombies or smaller crowds. Those two weapons burn through ammo unlike any other and if you use your primary weapon for everything, you'll soon find yourself armed with just a pistol and prayer when the Tank eventually turns up...
Melee
When zombies get close, the instinctive thing to do is turn around and start firing. Forget that. Just turn around while whacking Left Trigger - this is your melee attack and it'll hit the zombies away, so you have more time to fire. Why is this better than turning and firing? Melee attacks don't need to be aimed, so you'll save yourself a few extra bites from hungry zombie teeth - vital if playing on Expert.
Boom, Boom, Boom
Usually, when you come to an area when you can set off an ambush, you'll find petrol cans and gas canisters lying around. Try to scatter these near obvious points of entry for the zombies and special infected - when shot, they'll explode (killing nearby zombies) and spew flaming liquid everywhere (creating a temporary barrier).
Boomers
Boomers, who look like fat zombies, will vomit bile at you. If any of the team get covered, they'll turn yellow and zombies will now be attracted to them. If there are no zombies in the area, new ones will turn up.
A potentially nightmare scenario can be dealt with if you stay calm. Pipe-bombs override bile, so zombies will run towards pipe-bombs instead. If you have no pipe-bombs, just back yourself into a corner and shoot the zombies as they come towards you - the more you can funnel them towards you, the better. Finally, duck down so your team-mates can help clear the crowd without hitting you.
Hunters
There's no real way of anticipating a Hunter's attack, besides paying close attention to your surroundings when you hear your team call out the presence of one or its distinctive howl.