Why has it taken the XBox gaming developers such a long time to figure out that people like to play videos games in CO-OP mode. 

You may say that there have a been a lot of multiplayer games in the past but they aren’t the say.  In a CO-OP game you are able to actually experience the game with other people.  Share in the same delemas and overcome them as a team.  

Left 4 Dead is one of the first games that I have seen where the experience relies on the players playing as a team.

Other games in the past have been quite successful due to this “play as a team” mentality where they are able to unite for a common goal.  Counter-Strike and Day of Defeat: Source are two games that have been popular for a VERY LONG time.  Before Halo, before BF2 and before Tribes.

So it is obvious that gamers have a clear draw to CO-OP based games yet there are sooooo many new games coming out that don’t maximize on the CO-OP experience or consider the level at which players will want to share the game.  I like where the people at Valve are going, as usual, and look forward to new games built off the results of this test run which is Left 4 Dead.