After having a good six hour session of Zombie fragging fun, I can safely say that the demo was indeed one of the largest cockteases I’ve ever had to experience.
Left 4 Dead offers some of the most spontaneous gameplay I’ve ever experienced in a shooter. The AI is beyond solid and provides a formidable challenge on Expert difficulty. Although we only got to the last part of the first scenario, the areas after the demo area provided an awesome experience each time, especially the interior hospital areas. Dying or becoming incapacitated in this game is almost as enjoyable as completing an area of the game, and on more than one occasion, provided significant amounts of hilarity in the method of which the deaths occurred (for instance, Francis shooting Zoey in the face while incapacitated and a fart and a pancake away from the safe room….)
The level design, at least in the hospital level, is solid. It’s nothing fantastic, but it’s grim and gritty, but retains the cartoon-esque quality Valve is known for. I especially enjoy the writing on the walls - graffiti, seemingly written by other survivors. Messages to loved ones. Zombie kill counts. A discussion on how and why the infection happens (”It takes 3 days to happen!”, “I saw it happen in 2 1/2 hours!”, “No, it only happens at night” - crossed off, and scribbled underneath: “That’s Vampires, moron!”) And then there is Chicago Ted - who seems to really enjoy killing zombies (”No Zombie is safe from Chicago Ted!”) It fits and adds a sense of realism to the game. The actual zombies themselves are numerous - but varied enough that aren’t just killing Zombie Model #01, #02, and so forth. Outside of the hospital, the zombies consisted of businessmen, usual people, police officers, army soldiers, and so on. As we got closer and closer into the hospital itself, the zombies were doctors, nurses, and patients (complete with hosptial gown and exposed buttocks.)
The AI - perhaps it’s because Left 4 Dead is a zombie survival game, but I think that the AI is the single crowning achievement of this game. Not just the zombies, which provide ample challenge for a scripted monster, but also for the co-operative AI. At any time, you can “take a break” from the main menu, and allow a somewhat knowledgeable AI to control your character. There is also Valve’s “Director” AI - the technology powering the randomness of the game: where zombies spawn, where ammo tables spawn, where ammo and grenades spawn, where the special monsters spawn….
The special monsters are the source of numerous “oh, fuck” moments. Witches are female zombies whose sobs and cries can be heard from a couple meters away and provide enough warning to switch off flashlights - since they are startled by light, the flashlights do nothing but startle them into a frenzy, during which their attacks are generally a one hit kill. There are boomers - fat, bloated zombies which die in a single shot, but can puke and impair your vision (rendering friendly teammate indicators null), and also explode, dealing damage to any survivors around them. Smokers are frog-tongued zombies, which lash out with their lengthy tongues and pull survivors away from the group. Hunters are vampire-esque types that jump long distances, and pin a survivor to the ground, rendering them useless until the hunter is incapacitated by a teammate. Lastly, the Tanks - giant, monstrous zombies which through chunks of rock, forklifts, and anything else they can get their hands on at survivors, and take a good forty to fifty seconds to kill, assuming that everyone survives during the attack.
The difficulty settings could stand to be tweaked somewhat - I dislike having multiple “tiers” of difficulty settings. I’d love to be able to tweak and change difficulty settings - for instance, on “Advanced” difficulty, friendly fire does about half the damage it does on Expert mode. It would be nice to have a slider adjust option to change the strength of the zombies to maximum, while toning down the friendly fire a bit. Although this became less and less of an issue as the night went on, as we generally found out that - yes, you do have to work together, and, yes - you best be using voice comms and barking orders as much as possible to survive.
In the scope of games this year, Left 4 Dead could easily be a Game of the Year. Fallout 3, was good, but no where near as innovative as Left 4 Dead. Valve’s attention to detail and understanding of their customer base really shine through in all their products, and Left 4 Dead is no exception - it’s something new and different, taken under the care of Valve, and lovingly carressed and polished until the final game experience is nothing short of memorable. Make no mistake, this game is also on the 360, but Valve is a PC gaming company. The game is meant to be played with WASD + Mouse, and you also get the benefit of Valve’s free content updates by getting it on PC - instead of having to pay for Xbox online services.
All this is just my experience from the Co-operative campaign. I can’t even imagine the hours of play Versus mode will offer, but I’ll go on a whim here and say that it’s going to be every bit as enjoyable as the co-operative campaign. I really want to play some more, but I’ve got to wait the eight hour work day out 
