Half-Life 2: Episode Two Q&A - Story, Setting, and Technology

Almost a full year has passed since Valve released Half-Life 2: Episode One, the first of three promised episodes that will continue the saga of the blockbuster first-person shooter franchise. Episode Two was originally scheduled for release late last year, but Valve pushed the release date back to later this year. When it does arrive, it will feature not only the continuing story of series protagonist Gordon Freeman and partner Alyx Vance battling the alien Combine, but also the multiplayer action game Team Fortress 2 and a 3D puzzle game called Portal. To learn more about what's going on in Episode Two, we caught up with Valve project manager Erik Johnson. A warning to those who haven't played Episode One yet, as this preview contains spoilers to major events.

GameSpot: Obviously, we're not looking for spoilers, but what can you tell us about Episode Two's story? At the end of Episode One, it seemed that a major chapter had come to a close with the escape from City 17. What's next to come?

Erik Johnson: The Citadel's destruction triggers formation of a massive superportal. To close the portal and prevent the Combine from sending reinforcements, Gordon and Alyx must make sure the data packet they seized in Episode One gets to White Forest, a former missile base where their scientist friends and family have made their stand. It's a breakneck run through an alien-infested wilderness patrolled by Combine troops, marked by encounters with mysterious entities. If they make it on time, they stand a good chance of shutting down the portal. If they fail, then, in the words of Eli Vance, "It'll be the Seven Hour War all over again. But we won't last seven minutes this time."

GS: It's been reported that Episode Two will be longer than Episode One. Could you elaborate on that? Will it be approximately as long as Half-Life 2? Slightly shorter?

EJ: Our play tests of Episode Two are running closer to eight hours, where Episode One was taking around six. If you take a look at the statistics we compiled from people who actually played through Episode One, it looks like the average completion time ran around five hours, 41 minutes.

GS: Will vehicles return in this episode? Half-Life 2 featured the dune buggy and the air boat, but Episode One took place entirely on foot. Will either of those vehicles return, or is there something new to look forward to?

EJ: There will be a new vehicle in Episode Two. The buggy from Half-Life 2 was built by a group of rebels that was clearly skilled at welding together a tube frame but was a bit lacking in the horsepower department. In this episode you'll be driving a car built by someone with a lot of knowledge of older American hot rods.

GS: What can you tell us of the major characters, such as Alyx, Dog, and the G-Man? What are they up to? And will we meet any major new characters in Episode Two?

EJ: Most of the characters will be back in Episode Two, including the G-Man. Since the Vortigaunts stepped in at the start of Episode One and pulled you out of the G-Man's control, he'll be coming back to enlighten Gordon on a number of events and give you some insight into his line of thinking. There will be some new additions to the cast in Episode Two, as well.

GS: Will Episode Two introduce any major technological improvements to the Source Engine? For example, Episode One introduced high dynamic range lighting. Will Valve use Episode 2 to introduce DirectX 10 support in the PC version?

EJ: We've been building more technology into Source alongside the development of Episode Two, Team Fortress 2, and Portal. Episode Two specifically will be taking advantage of cinematic physics, which gives us the ability to create large-scale destruction events that are physically simulated. You'll see that feature in action right at the beginning of the episode.

Meanwhile, the visual budget for Episode Two is higher than Half-Life 2 and Episode One, so we essentially have a higher "high end" on the graphics side. We made this decision as a result of tracking the rapid GPU adoption rate of gamers on Steam via our hardware surveys. Having moved to episodic development, we are able to more accurately target these early adopters and provide an experience that does a better job of scaling to the power of their systems. And we've built a new particle system into Source. This has put more of the control of our visual effects directly into the hands of the artists, resulting in the most graphically sophisticated game we've ever made.

GS: Computing power has increased substantially since Half-Life 2. PCs now have dual-core CPUs, and the Xbox 360 and PS3 are powerful multicore systems. Will Episode Two support multicore CPUs for better physics or AI?

EJ: We've built a system for dealing with multiple cores and threading called hybrid threading. As opposed to using coarse- or fine-grained threading, we take the approach of building a system into the engine that makes the right decisions about how to deal with multiple cores on the CPU.

In Episode Two this will translate in a number of ways, benefiting not only systems that were traditionally CPU based, such as artificial intelligence and physics, but also systems that are on the graphics side. We went with this approach because it scales well over time. Desktop processors are going to have more cores over time for us to take advantage of, so we took the route that requires more work up-front so we can keep pace with our customers' hardware as we move from dual core to quad core and beyond.

GS: Finally, when can we expect Episode Two to ship, and will it ship on all three platforms simultaneously?

EJ: We're looking to ship in the fall of this year, on the PC, Xbox 360, and PS3 simultaneously.

GS: Thank you.