As for where Aftermath is set, and the timeline, it's very much a logical continuation from where Half-Life 2 left off, as Laidlaw goes on to explain in the PC Gamer feature: "[Aftermath] deals with the events and issues set in motion during Half-Life 2. You've done critical damage to the Citadel. The whole place is going to go up, taking out City 17 and what's in its immediate radius. You and Alyx are leading the flight from the city getting up close and personal with some of the creatures and sights from the end of the game." Interestingly, the assumption that you continue to play as Gordon isn't justified anywhere in the text; it's possible - and perhaps more likely given the game's ending - that you play as someone else instead.

And unlike in the original, creatures that were barred from the confines of City 17 have now found a new home unfettered by the barriers that kept them at bay previously. "We have a philosophy that we try to re-use and provide interesting twists to our core concepts," says Harper in the same PC Gamer feature. "Like the Antlions started the game as your enemy, and then became your friends later on. In Aftermath, City 17 was 'one thing' and now it's this 'other thing'," he continues, refusing doggedly to elaborat despite probing from writer Tim Edwards.

PC Gamer also has information about 'The Lost Coast', the fabled high-end graphics level. According to Valve, the level will require 1GB RAM, a 3.2GHz processor and a top-end graphics card. One of the new features will be support for High Dynamic Range lighting. Interestingly, ATI - big-money sponsors of Half-Life 2 - don't support the industry standard for HDR lighting, which is OpenEXR. It will be intriguing to see whether Valve go with the industry standard, or ATI's kooky version