The build of Left 4 Dead 2 that Valve brought to Tokyo Game Show really wasn't that different from the version showed at PAX—with one exception, the addition of the chainsaw melee weapon.
The two level demo took place in the "Dark Carnival" campaign, the one that Totilo recently previewed during a visit to Valve. My play through of the third campaign so far revealed took a few tries to get right and a few to finally get the chainsaw to randomly spawn. But when it did, it was a force to be reckoned with.
Maybe a little too much of a force, as the chainsaw felt about as powerful—and as tangible—as a lightsaber from Star Wars. Slicing up zombies with the newest melee weapon seemed more disconnected than swinging an axe or frying pan, as the sound of chainsaw didn't pack much of a punch.
It was also the first melee weapon I'd used in Left 4 Dead 2 that ran out of "ammo". The chainsaw does appear to have a limited amount of fuel and, when exhausted, your Survivor will toss the weapon. That will ensure that the choice to pick up the chainsaw will carry with it consequences, even if it appears to be one of the more powerful melee weapons one can use in the game.
Beyond the ability to slice through infected humans like a knife through hot butter, we're not sure yet what special attributes the chainsaw might have. The fire axe, for example, is perfect for dispatching the Witch—there's even an Achievement for "crowning" the zombie with the axe—but Valve's Kim Swift didn't offer specific details on what the chainsaw would be best used for.
Outside of chainsaw usage, I got my first hands-on time with the laser sight add-on that makes firearms more precise and experienced my first battle with the Jockey. The former was a nice, if not immediately noticeable perk, but the latter was an impressive pain the arse. Battling the Jockey for steering rights—fortunately, no high ledges were nearby in the levels we played—should offer some interesting twists to multiplayer battles.
During our discussion with Swift, it sounds like there's still plenty to be revealed about the game, including the two remaining campaigns, their respective "uncommon common" infected, new environmental hazards and a few new projectile weapons. Keep an eye peeled for more to come.