Half-Life 2 (HL2) is, in my opinion, one of the best shooters ever made, both for technical and artistic reasons. Though Valve does require its players to jump through a few hoops to play this game, it is well worth it. The plot (or, in some cases, the lack thereof) belies a much deeper, overarching storyline that meshes well with the first HL. Additionally, HL2 sports some of the most realistic graphics and perhaps the most realistic physics engine thus far conceived in a game.
First, the technical achievements. The much-touted Source engine renders characters and settings beautifully. I found myself, on several occasions, just looking at some of the different materials in the game, just to see the shimmering effect as I walked around. While this may seem a bit childish, it is an effect only recently achieved and hardly perfected.
The water is also very well-rendered, especially if one has a higher-end system and can enable the "reflective" option in regards to the water. Again, this is a minor admiration, but still something tricky and as yet not well-done in games.
The physics engine is really where HL2 shines. The modified Havoc 2.0 engine describes animate and inanimate objects so well that it has proven difficult for me to play games that do not utilize the Havoc engine because they seem so fake. The player will take special interest in the gravity gun, a device that can "grab" inanimate objects and fling them around according to their real-world physics. Several of the game's puzzles are solved using either the physics engine, the gravity gun, or usually a combination of the two. The physics engine also describes objects floating in water, a feat that I've yet to see done well until HL2.
Facial expressions also exhibit state-of-the-art technology. I've never seen faces that looked so convincingly expressive. NPC's heads and eyes will naturally follow Freeman as he's walking around the NPC's. NPC's gaits and movements are all natural and fluid, just like an actual person's.
The interface is straightforward: The primary mouse button fires the primary mode of the currently selected weapon, while the secondary mouse button fires the weapon's secondary mode. Different weapons correspond to different number keys. A use key, a flashlight key, a sprint key, a crouch key, and a jump key are the only other keys that the player must know.
The only technical complaint that I have about the game is, of course, the Steam service. While I don't think Steam is all bad (I like not having to have the CD in one of my optical drives to play the game, as well as the check for patches and updates before the game loads), it certainly isn't the greatest thing to happen to gaming. While I understand Valve's paranoia in pirated copies of HL2, I think the Steam system was a bit much, like exterminating ants with a tactical nuclear device. Simply having the player register his key over the Net should've been fine, but now the player is required to create an account, login every time he wants to play the game he payed money for, and so on. It's a bit on the overreacting side in my opinion.
The gameplay represents solid level-design and decent squad AI. Firefights, especially in the urban areas, are, for the most part, reaslistic. The enemy AI displays decent intelligence, taking cover, attempting flanking maneuvers, and using grenades as indirect-fire weapons. The squad AI (though it could more effectively be called a fireteam) leaves a lot to be desired. While they do a good job of getting out of your way, they do not seem to know the advantages of cover. I wouldn't expect rebels in a game like this to know advanced infantry tactics such as bumping and bounding, room clearing, or fireteam/squad rushing, but they don't seem to grasp the concept of covering fire or mutually supportive fire, especially with the fully automatic weapons. These are simple tactics that I feel the game developers should've given your squadmates, as without them, they prove fairly useless throughout the game.
Other gameplay features include a few things that, while not unique, are certainly cool. Towards the middle of the game, Freeman picks up some "pheromone grenades" which can call antlions out to attack an enemy or follow Freeman. This makes for a much better "squad" than the rebels that you get later.
The gameplay also features several vehicle-mounted chapters. The hovercraft chapters I especially enjoyed, as it showed off the physics engine better than the dune buggy (plus it couldn't flip over). The dune buggy chapters were fairly fun, but having the dune buggy flip over at times frustrated the crap out of me, since antlions will attack the player until he can flip the buggy over using the gravity gun, and accomplishing that task involves shooting the buggy with the gravity gun multiple times until you hit it just right to flip it over.
Artistically, the game excels just as well. While many gamers and reviewers will disagree with me, I really enjoyed that so many questions are left unanswered. That Freeman never speaks only deepens the mystery and keeps the player in the dark about a great many unanswered questions posed by the first HL. I enjoy when plots are left in such an open-ended fashion, as it allows for speculation as to the true nature of the subplots. A quick Google search shows several "unified HL theories" that tie together the plots from both the games and the expansions. Many smaller "theories" attempt to explain characters, such as the enigmatic G-Man, or how Freeman ended up in City 17 ten years after the Black Mesa Incident.
The dystopian and Orwellian atmosphere of City 17 is also well-done, especially in the earlier chapters. The monitors that litter the area showing Dr. Breen's face while he explains that humans' instincts are their enemies is ominous, and the flying robots that take your picture and monitor your movement are a nice touch. The Civil Protection also fits in quite well with this dystopian reality, especially when you hear their voices as modified through their gas masks and their radio chatter. Unfortunately, once the game really gets going, these effects diminish quite a bit. The last few chapters show the inside of the Citadel, which is more streamlined and alien. While it isn't as stark a reality as the earlier levels showing City 17, it does make for interesting gameplay.
In all, I can recommend HL2 to anyone. The story remains interesting, though much of the plot stays hidden. The graphics and physics are top-notch, and the enemy AI behaves fairly realistically. While many gamers may say that the game did not live up to the hype, I would advise most people to realize that no game ever lives up to its hype because the media overhypes everything under the sun anyway just to sell magazines. HL2, while not perfect, comes pretty close, in my opinion.