Left4Dead Week: The AI Director – Part Three – The Rise and Fall

Left4Dead week will feature one short piece on Left4Dead each day this week to celebrate the full release of the game.

A number of reviews have highlighted the sophistication of the spawn system, so that you never see the director spawning zombies directly - they always appear off screen and then rush you.

What reviewers don't seem to have mentioned as frequently is the way the level design aids and abets this. If you're in a wide open area, you can be sure the zombies will be clambering over a nearby fence, crashing through windows or running over a rooftop. And in enclosed areas, you'll find holes in the ceiling from which they'll pour. The most elegantly designed area for this is the start of the first map for No Mercy, which features in the demo.

An in a post 9/11 world, Valve can't be ignorant of the significance of watching bodies falling through space.

(No Mercy has the best opening area of any of the first maps. For the best opening sequence of a final map, you'll need to play through Dead Air. At which point one of my fellow players yelled Game Over man, Game Over! the second time we watched it through.)