Thinking about it, there's more than a touch of the chat show audience about all of the newcomers, too: the Spitter, who gobs health-sapping goo; the dungaree-clad Charger, who grabs one luckless survivor and runs as far as it can with them; and the runty, vest-wearing Jockey, who leaps on your back and steers you away.
As with the existing Specials, they only serve a very specific function and are quickly dealt with. The Charger, particularly, is surprisingly weak for his size: it only takes a few blasts to finish him off, and the others aren't particularly tough either. But working together, their different attacks become absolutely lethal.
You can't hole up and defend for a while, because you'll get spat on or charged; you can't charge steadily onwards because the person at the back is going to get steered, charged or dragged away. It's bad enough when it's just the Director in charge; when human players take the reigns in Versus Mode, they enable some of the most sadistic takedowns Xbox Live has to offer.
Simply gobbing in a doorway can have a catastrophic effect on the Survivors' progress, line up a bull-running Charger correctly (which is very hard to do, 'cos he'll run some distance and you can't steer once he's moving) and you can set one of them back fifty yards, possibly permanently.
The Survivors do get a slight edge in the more open maps because it's harder for the Infected to find a hidden place to spawn, but any advantage is lost if they go ahead to destroy cover before you arrive.
Versus mode is joined by new arrival: Scavenger, a riff on the new finale events. You've got to collect scattered fuel cans to top up a generator, while the opposing Infected team try to stop you. Because it forces you to move around harvesting the cans, it opens you up for attack, and because you're collecting highly flammable material it opens you up for disaster.
Spitter goo degrades cans and makes them catch fire, so it's a tough choice between building a stockpile or going for the safer, but less efficient one-by-one approach. Have your discussion, and make your choice; you'll be dead in minutes either way, but hopefully you'll have racked up more cans than the other team. Picking a strategy, and working together to follow it, remains the single most important skill on either side of the dead/undead line.
Survival of the fittest
The co-op only Survival Mode, introduced in the Survival Pack DLC, also returns, with ten challenges you've got to survive for as long as possible. Fun though these modes are, we're betting the connoisseur's choice will actually be a riff on standard co-op: Realism.
We're looking forward to it because it'll instantly cull the morons who don't grasp the whole teamwork notion and think they can run on ahead.
It does this not by messing with the difficulty settings - you can play Realism on any difficulty - but by making a few crucial, horrible changes to the game: it doesn't highlight pickups, so you have to hunt for weapons. Witches kill you instantly. And, most importantly: there are no auras, so once someone's out of sight they are almost untraceable and almost certainly doomed.
Once, we paused to heal, didn't tell the rest of the team, and finished to discover we'd been left lost and alone in a knee-deep swamp. It was only the distant blood cloud of a Boomer exploding that revealed where the others were.
In campaigns like this, the Jockey becomes even more dangerous: once you've been steered a few yards away you'll probably never be found.
It's a really simple change, but it completely transforms the way you play: you might have thought you were a close-knit group before, but Realism demands teamwork that makes ants look free-spirited. The only crumb of comfort is that death isn't always the end, thanks to the new defibrillator.