First off, let me start by saying that for the sake of repetition, this is not a review of Half-Life 2, so I'm not going to rehash all of the aspects of Half-Life 2 and its engine, graphics and game play mechanics. With that out of the way, what I will elaborate on are the noticeable differences between the two games and the improvements made upon the first installment. Given that this is a sequel, of sorts, Half-Life 2: Episode 1 does a fantastic job at what it was meant to do. It is the first of three "episodes" to be released by Valve, taking right off where Half-Life 2 ended. As noted on Valve's website, you do not need to own the original Half-Life 2 in order to play Episode 1, although I wholeheartedly recommend playing through Half Life 2 before playing Episode 1 in order to get the full impact of exactly what is going on, and to make any sense of the intro sequence at all.

The game really does throw you right back into the thick of things, resuming the story and exact feel that Half-Life 2 ended on. A few minutes into the game, and you find yourself knee deep in action yet again at the heart of the Citadel. Aside from some story at the very beginning to reintroduce the characters and remind you what was going on at the end of Half-Life 2, the game manages to keep a furious pace, and the action is almost always hectic. The game seems to play out much like an amusement park ride at first; tons of beautiful eye candy and things going haywire all around you, but just when you start to feel somewhat like a spectator the game begins throwing all kinds of obstacles at you, and the game transforms from a ride, to an interactive cinema of sorts, and effectively becomes a complete experience.

Though the game is built with the same engine as its predecessor, it has undergone some slight reconstruction and graphical improvement. One of the more noticeable things you see right off the bat is the addition of falling ash/dust particles throughout all of the outdoor environments in the vicinity of the ominous, burning Citadel (which in itself looks incredible). The second thing you may notice is that the facial expressions have been beefed up to add more of a sense of emotion, and that Valve's HDR post-processing has been applied to many more shaders and environments. So you're going to see a ton more bloom effects, which isn't a bad thing, as it helps the game look that much more polished.

The next major improvement that hit me like a ton of bricks was the game's visual and aural dynamics when compared with the original Half-Life 2. What this means in terms of visuals is basically that lighting drastically varies from scene to scene. The entire ambiance of the scene is quite different for every environment you encounter. You will quickly notice how much you come to rely on your flashlight this time around and how your once seemingly infinite hazard suit power supply is now more of another aspect of the game that you have to ration. You will find yourself in more than one situation where the lighting really affects gameplay and creates for a more interesting experience, such as using the flashlight to illuminate targets in a pitch black area so that Alyx can lend you some fire support while you try desperately to find flares (strewn about the various locales) as your flashlight power dies.

The game also seems to be more dynamic in the audio department with compared with Half-Life 2. That is not to say that Half-Life 2 didn't have great sound, but it seems like the music and sound effect touches were implemented into Episode 1 with more care, adding greatly to the overall experience and feel of the game. This may be due, in part, to the fact that it is a much shorter game, giving the designers the freedom to use the ambient music cues in closer proximity to each other without it getting tiring and annoying as such things might during the span of a full 20-40 hour game. The point is that the game feels like it has become much more of a complete experience, with the polish you might expect from a motion picture today.

As for the gameplay itself, many of you, much like I, may have been weary when this mini-sequel was first announced, dreading that it might fall into the standard "expansion set" category: loaded with token new weaponry and new, unfamiliar territory. This is definitely not the case here, as this game is literally an extension of Half-Life 2. The game plays out just like the original, feeling much like the welcomed return of an old friend. There are a few new elements and tricks to be learned over the course of the game which add to it's diversity over the previous installment, but the game remains mostly unchanged. This is certainly for the best, as Half-Life 2 played like a dream. One thing players had better get used to is much more use of the gravity gun early on. Episode 1 is packed with areas in which the physics gun is your primary tool, and you're going to need to get pleasantly creative with its use as you traverse the different levels.

Another aspect of the gameplay this time around that changes things a little bit is that you really need to conserve ammo early on. For all of you who were getting used to the trigger happy ways of Half-Life 2, be warned, as Episode 1 will see you quickly run out of resources, and checking every nook and cranny in the area for supplies. This fact ends up making the game much more interesting, as Alyx fights alongside you through almost the entire Episode. You end up using her more as a comrade aiding you in dispatching the various enemies in the game, and she actually ends up helping rather than hindering your progress.

The enemies themselves are, for the most part, the same that you encountered in Half-Life 2 (Combine soldiers, Combine elites, snipers, gunships, zombies, the antlions, etc.) though there are some twists thrown in. Such is the case with the "Zombine" (named by Alyx, not me) soldiers, who were Combine soldiers now infected by headcrabs and move a great deal faster than the standard headcrab-zombies. To add to their deadliness, the Zombine soldiers are armed with grenades, which tend to cause a lot of chaos. There is a nice variety in the enemies this time around to keep things fresh, and you'll find yourself in more than one sticky situation, being attacked by many different types of enemies at once, even stumbling upon battles already in progress between the Combine soldiers, antlions, and the zombies. I don't want to give away too many of the surprises and cleverly crafted situations in store when playing Episode 1, but I will say that the game manages to keep a refreshingly new feel to it, dropping you in pleasantly challenging situations that actually require a degree of thought and problem solving skill. Valve has really done a fantastic job making an already terrific game shine even more.

One last example of how Valve has added a nice little "icing on the cake" touch to this game is the optional "Lost Coast style" commentary mode. For anyone that did play through Half-Life 2: The Lost Coast (Valve's way of letting the public have a view of the design process and how the team overcame different technical obstacles), this mode will be very familiar to you. For those of you who have not played through The Lost Coast, this mode is a great way for you to see the thought process that went into creating this game, as well as all the tricks they used to bring the game to life. Think of it like a behind the scenes documentary on the game that plays out while you play through the story. While playing in this mode, "speech bubbles" are placed throughout the game, activated upon the player centering their cross hairs on it and hitting "USE." This activates an audio track recorded by different members of the design team explaining how they developed the graphics, gameplay and other aspects of the game. This is fantastic addition to the game once you've played through, so that the player can see where the different ideas came from and appreciate a little more the amount of effort and work that goes into a production such as this.

On the down side, the game is not without its shortcomings. In Half-Life 2, players saw the game take a very linear turn when compared to the revolutionary free-roaming first Half-Life game. Half-Life 2 did offer some options when it came to direction, though the player still followed the same basic path. Episode 1 basically cuts out any non-linear gameplay there was in Half-Life 2 and forces the player to follow the exact path laid out before them. The game still plays out well, but it is sort of disheartening to see such a totally linear game in the industry today force feeding you a given path to take, but it is hard to find fault in a game that is such a great experience to play. This really adds to the feel of the game being more of an interactive movie, and whether this is truly a good thing or a bad thing can be boiled down to a matter of preference.

One more caveat: The game is VERY short. Most players who were able to play through Half-Life 2 with minimal difficulties should be able to blow through Episode 1 in well under 5 hours on their first run. This definitely seems to be a one-sitting game. The only reason I think this hurts the game (and this would apply for pretty much all episodic games) is that you dish out about $20 for an experience that is over just as you are really starting to get into it. The price to gameplay ratio ends up being about the same as a full production game. Basically, you're paying around $60 for anywhere in the vicinity of 20 hours of gameplay. One can't help but feel some disappointment after beating the game without even having to take a bathroom break.

All in all, however, the game does not fail to impress, and follows up Half-Life 2 as a worthy sequel. And this is no easy feat given the game that it is following. There are far too many fantastic aspects of the game and general polish to outweigh the somewhat insignificant issues outlined above. The commentary mode on top of everything else really seems more like a great send off after beating the game. You get to unlock all the mystery behind and get sort of a recap on everything that happened while you were playing through. Valve really has done a great job showing people that episodic content doesn't have to be such a bad thing and can give the developers a chance to implement changes to the code as hardware becomes more and more powerful with time. The game is absolutely worth playing through and should not be overlooked in any case.