But first, some notes on Half-Life.
Half-Life was not a revolution. Some people talk about the importance of innovation, how games like GTA and The Sims where so succesful because they came out of nowhere and were entirely new, but Half-Life showed that it is possible to create quite a splash simply by taking a popular genre to the next level.
Half-Life came out less than a year after Quake 2, and was very similar to it: a linear funhouse walkthrough in a science fiction setting with monsters and the like. Quake 2 was no slouch of a game, but somehow Half-Life ended up making history and Quake 2 is only dimly remembered. What made Half-Life such a classic? Both Half-Life and Quake 2 had continuous worlds; both Half-Life and Quake 2 had story; both had the best enemy AI to date.
One thing Half-Life is that Quake 2 is not is a triumph of simulationism. Half-Life tries its darndest to answer the question, "If we accidentally opened a dimension for alien creatures, what would it really be like?" Many aspects of the game support the simulation: the guns are real-world guns; powerups always have a reason for being where they are; the enemy AI is incredible - as if you were facing a real team of coordinated soldiers instead of zombielike monsters that just rush you en masse; and there's a storyline that's internally consistent.
About the only concession Half-life makes to gamism over simulationism is Gordon Freeman is very hard to kill. Over the course of the game he probably takes around a thousand bullets.
Another thing Half-Life did was immerse you in the story instead of alternating story and gameplay, Ms. Pac-Man style. Not everyone has played Half-Life all the way through; but everyone who played it at all remembers the opening sequence - the trainride that gives you an overview of Black Mesa, followed by the bang-up, James Bond beginning with the exploding equipment and the invasion of the creatures, with you in control the whole time. When a scientist is snatched by creatures right in front of your eyes, you have to ask yourself: "What if I got here later? Would I have missed this event?" The answer, I'm pretty sure, is no: the game triggers the cutscene when you're close enough. Still, the illusion is convincing.
We've experimented some at Treyarch with our third-person games, trying to eschew cutscenes in the same way that Half-Life does, and it is an incredibly difficult task. It seems that the player is always facing the wrong way, or the critical events are too small on the screen, or the player will be able to interfere with the events of the in-game-cutscene in some unexpected way, and we always give up and revert to the tried-and-true cutscene. The Half-Life aesthetic requires painstaking work.
Obviously, if having a story was all it took to make something good, then all movies would be the same. All stories are not created equal. Half-Life has a story that is more interesting and believable than Quake 2 without becoming the didactic overwrought melodrama that is Metal Gear Solid. There are multiple factions: the aliens, the man in black, the Black Mesa scientists and guards, the opposing force. How they interact is interesting to unravel. The story is internally consistent. The story gives us a character that is a little easier for videogame geeks to identify with, I think: Gordon Freeman, the scientist who, in a pinch, can grab a gun and kick ass. A nice change from the musclebound thugs typical of video games. And the story purposely leaves things unexplained, left out: you feel like there's a rich backstory, a world, which you only see a slice of. The tip of the iceberg. So Half-Life is a triumph of narrativism as well as simulationism. (http://www.indie-rpgs.com/articles/1/ for gamism-narrativism-simulationism)
And, of course, it's a fun game as well: the enemy AI provides not only realism but also interesting choices, and the level design, which has a habit of showing you a goal and then putting some obstacle in your way that you have to navigate around, is addictive.
So Half-Life represents a no-compromise triumph; no matter what style of game you prefer, Half-Life shouldn't alienate you. Perhaps their consensus-building cabal approach helped acheive this.
So what does Half-Life 2 bring to the table, beyond better graphics and the best facial animation system ever seen in a computer game?
One thing it doesn't do is mess with the Half-Life formula: it must have been tempting to give Gordon Freeman a voice, but they resisted the temptation. The thing I noticed most about Half-Life 2 is that it's incredibly toyetic. "Toyetic" was a word given to me by a friend who used to work at Mattel who doesn't like being mentioned in my blog. It means, "like a toy." An amusing sidenote is that the guys at Mattel are trying to make their toys more like computer games, while we're trying to make our computer games more like toys. Or toy chests, anyway. The collection of guns in your typical FPS are already toyetic; a set of toy guns, each with their own kind of play. Half-Life 2 gives us a bunch of new toys above and beyond the usual collection of weapons: the air raft, the gravity gun, the dune buggy, the ant lions, portable gun turrets, squads of soldiers. Each toy comes complete with a context to make it interesting, and makes Half-life 2 feel like a brand new game, not a rehash.
Once upon a time there was a game called Trespasser that boasted the most realistic physics yet seen in a computer game. The game was universally reviled: "a crate stacking simulation" it was called. After its release, physics was avoided like the plague by game companies. It wasn't until recently that Havok made physics desirable again. Although Max Payne, Thief, and Deus Ex all have realistic physics, the physics in those games seems mostly like a cosmetic add-on. Half-Life 2 is the first game to make physics a part of the gameplay, with the creation of (admittedly contrived) physics puzzles. These puzzles are at the perfect level of difficulty for a mass-market computer game: difficult enough to be nontrivial and make you feel somewhat clever for solving them, but not so difficult that many people are likely to shelf-level-event on them. I never had to consult gamefaqs to complete it.
The story in Half-Life 2 is even better than the story in Half-Life. A dystopian future in the aftermath of the Black Mesa incident, it fills in some of the details missing from Half-Life but still leaves us hungry for more information. The way the Combine uses missiles loaded with headcrabs to pacify the populace of the city feels like something Larry Niven would write.
A rule they had in the making of Half-Life was they weren't allowed to develop technology unless it was going to be used in the game at least twice. I'm not sure, but it seems like they increased that number to three for Half-Life 2, which does help make the game a little longer. When you have quicksave, it does seem necessary that you reuse the same gameplay a few times.
The biggest complaint people have with Half-Life is the ending, where you go to Xen and do jumping puzzles until you get to the final boss fight. It was frustrating, the rules of the game seemed to change, it wasn't the kind of gameplay people had been enjoying so far. About all you could say for it was it made for a nice change after a lot of shooting. Half-Life 2 did not make the same mistake. There's an unwritten rule that the final level and final boss have to be the most difficult part of your game. Lately a school of thought has sprung up that this is not what people want. They actually want an easy but spectacular ending. Half-Life 2 tests the theory, by giving you an incredibly powerful gun that makes the final level and boss fight pretty much a cakewalk, but a spectacular cakewalk, as you're kicking so much ass. So it's not one of the many games that I played all the way to the final boss and then quit.
Half-Life 2 almost never felt like a slog. Almost every other FPS I've played have sequences or levels which seems like more of the same old thing, a drag. In general, with Half-Life 2, when I got tired of a sequence, I'd get to the end, and a new kind of gameplay would be introduced. I wonder if they cut sections that were deemed too boring, or if they've found the magic formula for how to keep a game interesting.
I feel like I need some paragraph to sum up...but since the Half-Life phenomena seems like a lot of subtle aspects that work together to form a whole greater than the sum of its parts, I'm not sure what to say. And I'm hungry now. Must eat.