As u probably know it's Me and Max (Ben) who are the forum Moderators, and we'll do our best to keep Nod69 active also in L4D. Also we will ask you for your opinion on certain stuff.
Left 4 Dead The game info: Left 4 Dead is one kind of zombie game where u travel from one safe room to another, And on the way to one safe room you can find many different things such as:
Molotovs Effect: When u throw a molotov it will break apart and unleash a raging fire that will burn the zombies close to it.
Pipe Bombs Effect: Pipe Bombs are mostly like the HE-Grenades from CS:S except that Pipe bombs looks like a metal stick and takes more time before it explodes. Also the zombies run against the pipe bomb when thrown because of it's ticking sound and red blinking light
Gas tanks Effect: Gas tanks are tanks u usually re-fuel your car with but not in this game. In this game (L4D) you throw the gas tank somewhere (Visible or hidden) and then shoot it and it will have the same effect as a molotov.
Pain pills Effect: With pain pills u can regain a certain amount of HP for a short time.
First aid kits Effect: With first aid kits you can heal you or one of your friends for a amount of HP depending on their current HP.
Propane cans Effect: Propane cans has the same effect as the gas tank except that a propane can explodes instead of starting a fire.
Special Zombies
Boomer Special attack: Boomer bile Effect: when a boomer biles on you, you can barly see the zombies coming against you. Also boomer bile attracts the horde and almost forces it to attack you.
Hunter Special attack: Pounce Effect: When you are pounced by a hunter you can't move or shoot, and the easiest way to avoid him pouncing you is to stay together with your teammates and they will push him off you if u'r pounced.
Smoker Special attack: Tounge snare Effect: When a Smoker Ensnares you with his tongue u have a few seconds to shoot him down before he gets u trapped/incapacitated.
Tank Special attack: Throw Effect: The tank is like a tank in WOW with much HP as hell, just that a tank in WOW has several skills/spells and weapons, a tank in L4D uses nothing but his bare hands to kill the survivors.
Witch Special attack: None Effect: The witch mostly sits in a corner or something and cries, do not disturb her because on easy she'll incapacitate you and on Expert she'll kill you with one single hit!
You forgot to add that Pipe Bombs not only explode after a while, but they also lure Common Zombies with its sound and light. Thus giving you a great chance of escape or massive Zombie death.
Don't edit my post just to add the word "Succeed" because you should edit only your own FIRST post with information that WE, the people who know about L4D tell you. Which you forgot somehow.