WARNING: SPOILERS AHEAD...
Valve's David Speyrer and Marc Laidlaw reveal the secrets of Half-Life 2's second episode to Jamie Sefton: why you can't lose Alyx, the tear-jerking ending and their plans for Episode Three
While the long delay of the game's release stretched the idea of what episodic gaming actually is, Half-Life 2: Episode Two remains a triumphant expansion to the universe, taking your character of Gordon Freeman and his sassy sidekick Alyx on an epic trek to the White Forest resistance base.
On an eventful journey, Alyx is attacked and left unconscious by a new deadly opponent - a Hunter - Gordon discovers a complex underground Antlion cave system with the Vortigaunts, and the battle for Earth is taken out into the open with the help of a new super-powered muscle car and a helping of lethal Strider Busters.
The man in charge of bringing Episode Two to your hard drive was project lead David Speyrer, who joined Valve just as work on Half-Life 2 started back in 1998. Speyrer began our interview by explaining how the development team always examined scenes carefully in Ep2 through playtesting, and ruthlessly cut anything that confused the player - even if it meant changing ideas already revealed to the gaming public...
"If you remember watching the trailer that we did for Episode Two, there was a bit where Alyx was dangling over the deep canyon. There were a lot of issues with that sequence, the worst being that Alyx falling as a result of the train crash didn't create any interesting tension between the player and the Hunters as an adversary.
"Testers mashed the use key to try and figure out how to catch her before she falls, and then they go down there, see her unconscious and really want to help her, but there was nothing they could do but wait for the Vortigaunt. We don't have an administer first aid button!"
Speyrer felt that the sequence they eventually created with the Hunter was infinitely more effective, as the player knew very clearly that Gordon was trapped and immobile, and simply had to watch helplessly as the enemy punctured poor Alyx.
The difference between a good and a truly great game is in the polishing, and Episode Two had numerous balancing issues throughout its development. For example, in the level where you're being chased by the Antlion Guardian, Speyrer found that finding the right balance of being just challenging enough was very difficult, and took months of work to get it right.
"The original version was a lot more maze-like and players would just get incredibly lost. So, we did a pass of adding unique landmarks so that the player would know if they ended up at the same intersection twice, and then we then tilted the whole map so that you'd know down was one way and up was the other - but still it wasn't enough. We then lopped off a couple of loops to simplify the geometry and added the drop-downs, which kind of force forward progression, because you can't get back up them. I also think reworking the lighting and making the little crawl tubes high-contrast really helped, as it led people into them."
At this point we were joined by the game's writer Marc Laidlaw, who as well as being the franchise's scribe, has also written many short stories and books, including Neon Lotus, which was nominated for a Philip K. Dick Award. One of the burning questions we needed answering was why the team felt they needed to bring in a new character, Dr Arne Magnusson?