Valve has been telling us that episodic content is the future of gaming for some time now. Ever since we were introduced to Steam several years ago, digitally distributed games advanced through regularly updated chapters was supposed to be the new model for the industry. While Steam has proven its merits in other applications (auto updates, friends list, no need to keep track of CD's anymore) no game has really utlized the ability to do episodic content, until now. Today we have the first chapter from Valve in their followup to the biggest sequel of 2004.

After Half-Life 2 ended with a cliffhanger, gamers were worried that it would be another agonizing wait for their next installment in the Half-Life saga. Fortunately for us, Valve had all the tools they needed in the Source engine to continue the story as they see fit. That isn't to say there haven't been some slight changes to the graphics, but I'll talk about those a little later. Since this is a review of a sequel that EVERYONE should have played, I'm not going to worry about any spoilers about the story from Half-Life 2. If you haven't played Half-Life 2 yet, stop reading right now, log on to Steam, and play through it. Then we'll talk.

Episode One picks up at the dramatic end of Half-Life 2. The reactor at the top of the Citadel has been destroyed, with Gordon and Alyx set to be engulfed by the ensuing explosion. I won't tell you how they get out of this precarious situation, but suffice to say it feels like something of a cop-out. It also helps to push the G-Man out of the storyline for the rest of the episode.

The story for the rest of Episode One revolves around Gordon and Alyx escaping City 17 from the collapsing Citadel. Notice I said 'Gordon and Alyx'? The majority of the game has Alyx fighting along side you and helping to solve puzzles. In past first person shooters, AI controlled sidekicks have rarely been a welcome sight. Fortunately Alyx suffers none of the typical issues associated with AI teammates. Her pathfinding is always excellent, and you actually feel like she's helping when she's mowing down zombies or Combine soldiers. She proves to be an entertaining companion as well, as the dialog between her and Gordon oscillates between desperate and flirtacious.

It's fortunate that Alyx is along for the ride, otherwise it would be difficult to distinguish many of the levels in Episode One from its predecessor. It's unfortunate that the story of their escape from City 17 must be told in order to continue the saga because most of the environments are ones we've seen before. Without Alyx, running through the streets fighting Combine soldiers wouldn't seem all that different from Half-Life 2. One of the more memorable levels comes in a pitch black tunnel where you're forced to let Alyx do the shooting while you keep the her targest illuminated. It's a creative gameplay element that makes you feel like you and Alyx are really dependent on one another to survive.

Valve's Source engine is still considered one of the most technically capable for the PC, but did that stop them from tweaking it? Nope. Episode One incorporates the same HDR lighting first displayed in the Half-Life 2: Lost Coast. In addition, Valve has added a new color correction option to the engine that attempts to replicate ambient light more realistically. If you've got a computer fast enough to turn up all the details, Episode One truly shines. The good news is that if you're PC isn't up to snuff, the engine is still very scalable and should run on older machines. It looks like some of the character models might have received upgrades from their HL2 counterparts, but that might just be the HDR talking.

Unfortunately Episode One is over as soon as it begins to pick up. It ends rather abruptly after several escort missions that seem tacked on to try and extend the gameplay by 30 minutes. In all honesty, a competent FPS player should be able to complete Episode One in less than 5 hours. This short amount of time doesn't allow Valve to answer any questions from Half-Life 2, though they did somehow manage to create more. A nice little treat that adds to the replay value is the inclusion of developer commentary. This is essentially the same as the commentary tracks that are on most DVD's and provide some interesting insight in to the development of the game. It at least warrants another playthrough of the game so you can learn more about how Episode One was created.

When all is said and done, the only thing I'm left with is an insatiable desire to play Episode Two. With a bargain price of $20 Half-Life 2: Episode One is a requisite PC experience. I just wish they had pushed the envelope a little more like they did in Half-Life 2.