We do head underground though, into the Antlion world. "In Half-Life 2 and Episode One Antlions just came out of the ground, and the implication was that there's this whole underground system of tunnels that Antlions lived in. In Episode Two, we take you down into those tunnels and you'll see new species of Antlions and fight them," says Speyrer. "You'll see the ecosystem of the Antlions from the inside." And so we do. Larvae on the tunnel walls crush underfoot and release suit energy to top Gordon up, and terrible screeches puncture the silence. They're from Antlion Workers, a new enemy that takes a couple of shotgun blasts to take down, fires corrosive balls of spit at you and scuttles and leaps with the agility of a regular Antlion. The world itself is an eerie, luminescent blend of blues, greys and light purples, with lots of water, stalagmites and tites jutting out of the ground and ceiling, and a brooding atmosphere that's evocative of the first plunge into the nest of xenomorphs in Aliens. Even though it's utterly different, it feels like a coherent part of the Half-Life world, and reminds us of Xen. Tellingly, Alyx is nowhere to be seen here, although regular Antlions are. But do we get to make them our friends again? "You'll have to play to find out," Speyrer says, giving nothing away.
One thing that strikes us as we tunnel through the Antlion world is the amazing underwater effect - exactly like swimming with your eyes open. "It's our best-looking game ever, which is owed a lot to the fact that we're targeting a higher end this time," Speyrer explains. "PC hardware has moved ahead a lot since we shipped Half-Life 2 and we've tried to stay right on the cutting edge of that hardware. We still scale down - although we're dropping DirectX 7, we scale all the way down for Episode Two." Episode Two borrows elements of DirectX 10 for those whose hardware can take it, although it's not fully DX10-based like Crysis. Not that we're complaining - the overgrown, grassy hills and rundown buildings that pepper the landscape feel at home within the context of the decay witnessed in City 17, and seem to go on for miles. Different, but consistent. Other new effects include phong shading, which gives greater depth and "sheen" to characters, who remain expressive. We can't help giggling when Alyx rolls her eyes at Magnusson's pomp. Meanwhile those Antlion workers even qualify for their own bioluminescent shader effect. Who else but Valve would bother?
We admit, at this point, to being surprised at how much is being shown. Looking back over the last two pages, you might be worried you've seen and heard too much. Lombardi and Speyrer move to reassure us, and that term "mini epic" comes up again. "It's a deliberate choice," says Speyrer of the decision to deal with so many things in Episode Two. "We wanted to really get people into a meaty story, and it's just part of the story we're trying to tell." Lombardi concurs. "I think any trilogy you look at, the second one is always the one that's got all the big reveals that get things charged up a bit." Plus, there's so much left to answer. The big criticism of Half-Life 2 and Episode One was that the cliffhangers swung us over a huge vacuum of information, so it's good to know that we'll get more insight into G-Man, Mossman, the Advisors, the Vortigaunts, and what the rest of the resistance is up to. Bear in mind, also, that we're told at the start of our session that the bits we'll play have been deliberately set up so that we don't get to witness anything that might spoil the experience.
Before we leave, there's time for one more battle, at the White Forest Inn about two-thirds of the way through the game. Steaming past it in the muscle car, Alyx and Gordon are suddenly caught fast in a Combine containment field and funnelled into the Inn itself, as the music ramps up and there's movement all around. What follows is an awesome battle on multiple fronts, as hordes of Combine troops and Hunters descend on the building, blasting holes in it and chasing us up and down the stairs, into the basement, and eventually out into the open. Gordon's on his last sliver of health by the time it finishes, five minutes later, and quite out of breath. It's a fitting climax. Which reminds us - there's speculation, kicked up by friend-of-the-website Tom Francis, of PC Gamer UK fame, that the trilogy will climax in the Arctic. "We're not going to spoil it," Speyrer says. "No matter what Doug said."
But, more important than all that, who the hell dies? The first trailer suggested Alyx was in trouble, but now it's plain that she's at Gordon's side for quite a lot of Episode Two. Are Valve just being mischievous? Perhaps not, says Speyrer. "It's not as much of a misdirection from what you would think when you play," he says. Mystery heightened. At least we got some answers this time though. And with Episode Two's completion potentially just five months away, we hopefully won't have to wait that much longer to get some more. Although, you know, Valve and release dates.
Half-Life 2: Episode Two is currently aiming for October, and will be released on PC, PlayStation 3 and Xbox 360.