
Key Idea's #1: Teamwork / AI
While one person is up front with the melee weapons the other players will either be watching the teams back or just killing zombies in the general protection of your team mates. The AI in L4D2 has really improved in some aspects but as well in some aspects it falters. Although artificial intelligence has come a long way their are parts to having it in games like this it has areas that need to be worked with a little more. If you have a charger on you and he is slamming you into the ground you're AI teammates will not be able to figure out whether to help you or to kill the zombies that are on them and then to help you. They are the best team mates if you have no intentions of experiencing online play because with online you get people who can change priorities depending on the groups need of assistance. The AI also has a problem of weaponry changes depending on the groups build up and also the picking up and using of explosive weapons. Now with a new game also will come new enemies that you have to

Key Ideas #2: Replay, Play...
Now with a game like this you might wonder "What do I do when I finish all the campaigns?". This was a big question when the first L4D came out, when the gameplay was finished the most you could do was replay all of them online on a harder difficulty with people you knew or maybe people you don't. Now while this really didn't get THAT old, it definitely got to the point of being a little routine. So how did the second L4D make up for the first? Well in the second

installment of Left 4 Dead a few things were added that significantly increased the difficulty and stress of the game, even on its lower difficulty. Now in both of these games, the difficulty of the level is based on two things. A.) Being the difficulty you selected, and B.) The game reads the players to see how well off on ammo the players are or how well off they are on health, the games in level difficulty will be judged by that as well. This area added on top of the amount of zombies able to be in L4D2 increases the difficulty of the entire game no matter what difficulty the campaign is set too. Now all of this added with the new zombies and the difficult terrains add in for some serious replay value. You can assure yourself that no matter what; each time you play this it will be different, whether its which guns appear where, or how many zombies come out of any given area at any time. This aspect of Play is very important, it builds a strong following in the gaming community when creators add in parts like this to make the game more enjoyable for everyone who puts money into this game.