Left 4 Dead 2 empowers AI director to change level layout

Where the new game pushes forward is in level design and changes to that AI director

The E3 show floor is packed to the gills with gamers from around the world, many of whom are waiting for their chance to play Valve's Left 4 Dead 2, the rapid-fire sequel to a game that only came out last year. Already played Left 4 Dead? Awesome! Then you'll be able to jump right in to its follow-up. Left 4 Dead 2 plays just like the original -- at least at first. It's still you and three other (albeit new) characters, blasting your way through zombie hordes as you try to escape to safety. And yes, the AI director is still tuning the excitement to epic proportions.

Where the new game pushes forward is in level design and changes to that AI director. Sure, there are other tweaks like the addition of such melee weapons as chainsaws (about time!), but those wouldn't be worth the price of a brand-new game.

That's why Valve has designed Left 4 Dead 2's levels to be fluid and changeable. If the AI director notices that a team of survivors is weaving through an area with a bit too much gusto, it'll close off shorter routes and make the goal a little harder to reach.

The objectives for every level of the game have also been shifted away from the now-routine "wait-for-pickup" finale that drives so many players nuts. Left 4 Dead 2's "crescendo" moments will all be unique to each of its maps. For instance, you might have to battle your way through a maze of chain-link fences to reach a tower at the center of the level and shut off an alarm that's calling every zombie for a hundred miles.