To anyone who has yet to play the original Half-Life 2: Stop right now. We're publishing this review under the assumption that anyone reading it has wrapped up the original game, so if you've yet to do so, turn right around, snag yourself a Steam client, and get crackin'. Go ahead, we won't go anywhere.

All squared away? Alrighty. So, when we last left Gordon Freeman, he had just been "saved" from a massive explosion atop the City 17 citadel by the dimension-travelling G-Man, who tossed him back into the nothing-space he came from at the start of the game. This left Alyx presumably left behind (and therefore killed in the explosion), and gave no indication of any of the aftermath of Gordon's actions. While the traitorous Dr. Breen had been toppled and the human population was in full revolt against their Combine oppressors, this still meant Gordon -- and thereby the player -- didn't get to get to see any of it. It was a literal fade to black.

'Till now, anyway.

Half-Life 2: Episode 1 picks up mere minutes after the conclusion to Half-Life 2, and right away it's clear that everything is well in hand over at Valve. The introduction is a perfectly executed triumph that sucks you right back into Gordon's world and doesn't let you go until the white-knuckle final boss fight...A little over four hours later.

Most people are aware of the twists and turns that saw the original Half-Life 2 to store shelves. The game's original source code was stolen and distributed on the Internet, there were massive rewrites to the plot, huge chunks of the game had to be altered or were cut, and the whole thing was mired in development for a full six years before finally being released. Anxious to find a way to get their product out the door sooner (or so goes the official explanation), the folks at Valve software have taken a new approach for this game that they hope will become a model for other games to follow. Rather than a full-sized expansion, Half-Life 2: Episode 1 is just over a third of the size of a full game, at just over a third of the price: $20.

Initially the idea of such a sort title seems off-putting, reduced price or not. But the more we think about it, the more sense it makes. This approach means that the games take less time to be developed and can thus get out the door sooner, and affords the creators a more hands-on approach to try new things without having to commit to a full-fledged development schedule for an entire game. There are three parts planned for this particular story arc to the game, and if you buy them all you're spending $60 -- probably what they would've charged you for the whole thing at retail anyway. You're ostensibly getting a better product more quickly with this approach, or so Valve claims.

Luckily, those are claims they've made good on, at least so far. Episode 1 is an absolute blast. If this is the kind of thing we can expect for episodic content from Valve in the future, then consider us officially converted.

We won't ruin any of the plot elements, but if you enjoyed the unique narrative of Half-Life 2, then you can expect more of the same here. You re-assume the role of Gordon Freeman and the plot picks right up mere minutes from where the end of the last game left off. As mentioned, anyone who didn't finished Half-Life 2 isn't granted much in the way of exposition; this approach has the benefit of tossing players straight into the next story arc without having to dwell on what's already happened, which works out better in the long run and keeps the pace flowing.

Gameplay wise, things have been tightened up from the original game a bit. The long, meandering travel stages from the previous title have been done away with in favor of a more condensed, specialized approach. The beginning of the episode is mostly puzzle-based, gradually giving way to more run-and-gun action as things progress. As before, most puzzles are physics-based and have multiple (and often quite subtle) methods of navigating them. A good example is a section where Gordon returns to the Citadel and has to crawl through a power duct where large energy balls are being fired from one end to the other. You can either sprint down the tunnel dodging the oncoming shots (which is what most players will probably do at first) or you can pick up something heavy with the Gravity Gun -- still one of the best weapons in a first-person shooter ever -- and hold it in front of you, deflecting the shots that way. Both approaches work fine, but the latter is a bit more satisfying because it makes you feel like you're getting away with something. As before, Valve are quite adept at allowing the players to feel as though they're being clever and "inventing" new ways to solve puzzles by adding in an obscure solution or two along with the obvious one.

The biggest addition to the formula this time around is that Alyx Vance is by Gordon's side for very nearly the entire episode. She sits out the puzzle-oriented beginning, but as soon as the fighting starts to pick up, she sticks to your side and doesn't leave until the credits roll.

While Alyx can die from being attacked by enemies, this is pretty unlikely to ever happen unless you're being completely negligent. She's more than capable of holding her own in combat, and will probably wind up saving your butt far more than you'll be saving hers. Behind the scenes, this was done by giving her a good-sized chunk of health that regenerates extremely rapidly, and a fairly powerful weapon with unlimited ammo; unless she's completely surrounded by enemies, it's almost impossible for her to be killed. This completely negates the "babysitting" aspect that normally sucks the fun out of plot-critical NPCs in these kind of games, and as a result you'll find yourself glad she's around instead of wishing you could kill her off.

She isn't just a glorified tank, though. Far more than in the previous game, there is a strong emphasis on Alyx's character. She'll congratulate you if you fight well, will offer hints if you seem stuck on puzzles, and essentially acts as an in-character narrator for the entire episode. She's not quite perfect; there will probably be a few times when you wish she'd pipe down a bit, and some of her dialogue is a little forced at times, but this is still the closest we've gotten yet to having a convincing, dynamic AI-controlled supporting character in an action game. Whatever nits are to be picked here are minor. She's an awesome addition to the gameplay formula and the work was clearly put in to make sure she added to the experience rather than detracted from it -- which is so often the case when you add an NPC to the mix in a game like this. Color us impressed.

Besides Alyx, though, the rest of the episode stays true to what was established in the original game. This isn't necessarily a bad thing, but anyone expecting a bunch of new guns to play with or baddies to use them on may be a bit let down. There is a single new enemy, a headcrab-possessed Combine Overwatch trooper (amusingly dubbed a "Zombine" by Alyx) who has the oh-so-fun habit of pulling out a live grenade to bludgeon you with, and a single new weapon...Sort of.

Remember the rollermines from Half-Life 2? Snag one with the gravity gun and hold it near Alyx and she'll convert it to your side. You don't get to use this all that much. It's intended more as a puzzle solution than an actual weapon. Even so, watching a pair of converted rollermines zap the hell out of a Civil Protection regiment is great fun.

On the technology front, the only big difference from the original is that now the game supports full-time HDR Lighting. What this means is that the light in the game will behave in a way that simulates how the human eye would react. So, in addition to bloom and realistic shadows, the light will also dim and brighten depending on how much if it you're looking at. Walking into a bright room will result in the screen looking very washed out and gradually dimming a bit as your eyes "adjust" to the level of light. The result is both impressive and very, very pretty to look at. It's used quite liberally throughout the entire episode, but always tastefully, so anyone concerned about things degenerating into an overblown light show need not worry.

Tie all this up with a good number of impressive set pieces and two very excellent boss fights and you have what amounts to a condensed, updated, rapid-fire dose of the same gaming goodness you got with the original -- exactly what we'd hoped for and then some. There are enough forward-thinking ideas here that the game doesn't feel like a re-hash, but it's still familiar enough to feel right at home with fans of the original. If this is what we can expect from the next two episodes, then Valve can consider them money in bank.

They also took the interested step of including a commentary system with the game as well, which is a neat little feature for anyone who's interested in just how much work goes into making one of these things. The same thing was done for the stand-alone Lost Coast level released a while back, except here it's far more extensive and covers a significant portion of the game design. We recommend playing through it once with the commentary off, then going in for a repeat play through with the system enabled. Same way you'd watch a DVD commentary. While some of the chatter is a bit dry and overly-clinical, that's really to be expected. These guys aren't movie stars, they're game programmers. Either way, it doesn't detract much from the overall experience -- It's a cool little feature that adds quite a bit to the overall life of the game.

Overall: 9.5/10

For all the trepidation about episodic content, it's clear Valve knows what they're doing: This game is a resounding success on every single front, and the fact that you're only getting a third of the overall experience just makes the wait for the next two installments that much more excruciating. If you played and enjoyed Half-Life 2 (and who didn't?), then you owe it to yourself to pick this up as well.

We're sold. Bring on Episode 2!