Despite the fact that it's only available on the Xbox 360 and the PC, this doesn't stop it from becoming a modern day classic.
On the Xbox 360 version of the game, there are a whole host of Left 4 Dead secrets that can be unlocked (also called achievements) by doing certain things in the game.
These are the most rewarding kind of achievements that you can unlock, since you actually have to earn them.
I have picked out a few of my favourite Left 4 Dead secrets and given a description on how to unlock them.
I have also included a list of how many gamerscore points each achievement gives you.
By far the hardest to unlock is 'What Are You Trying to Prove?', by which you must complete every campaign on the expert difficulty.
This achievement is justified by the whopping 35 that you're rewarded with.
Another challenge that I found particularly difficult was 'Man vs.
Tank', where you must Single-handedly kill a Tank.
As you probably know, tanks are the toughest enemies, and won't go down easily, so the 30 point bonus you get for competing this is definitely earned! The great thing about many of these achievements, is that they reward you for challenging yourself, or for playing the game in different ways.
For example, the 'Akimbo Assassin' challenge requires you to complete a campaign using pistols as your only weapons.
This really puts a new spin on the game, and keeps things fresh and exciting.