Of course, Gordon Freeman is back, but nothing we’ve seen so far indicates a trip back to the Black Mesa Research Facility. Instead, most of what we saw focused on an Eastern European locale called City 17. When asked about other locations for the game, Valve Managing Director Gabe Newell wouldn’t give out any other specific locations, but he did reveal something of interest, saying “the entire game will be set on Earth,” and that gamers won’t be visiting the alien world of Xen this time around.

Even so, it’s clear this isn’t any Earth we’re familiar with, at least not with all these aliens running around and such. How much time has passed since the events at Black Mesa? Valve wouldn’t tell us for sure, explaining that figuring out what’s happened to Earth in the past few years (and what Freeman’s been up to) is something you’ll learn over the course of the game. True to the game’s lineage, you know no more or less than Gordon Freeman: he’s just as lost as you, and you’ll discover the history of this brave new world right alongside him. You see the entire game through his eyes, there are no third-person scripted sequences, there are no movie-like cinematics, and you never even hear Gordon speak. As Newell states simply, “You are Gordon Freeman.”

As in the original game, you’ll have some help this time around. One of the key figures is girl named Alyx Vance, who, as it turns out, is the daughter of one of the scientists from Black Mesa. (“A child of this new world,” says Lombardi.) You might remember her father, Eli -- he was the only scientist “of color” to appear in the game -- and he returns for Half-Life 2 as well. It turns out Alyx’s mother was killed during the incident at Black Mesa, and she’s well aware of who Gordon Freeman is … although you may not be entirely sure yourself. Also returning: our buddy, Barney the security guard, who we last saw successfully escaping from Black Mesa at the end of Blue Shift.

Although nothing substantial, we were able to glean a little more info from Valve on a variety of topics. At points, you’ll be fighting with aliens from Xen, for reasons that have yet to be revealed. And, just as you fought the military in Half-Life, you’ll find yourself in combat against City 17 personnel. Vehicles will be present and play a major role, and they won’t just be preprogrammed objects on a rail; you’ll be in full control and will need them to get from one area to another quickly.

Half-Life 2 is developed by Valve Software the creators of Half-Life. In conclusion, Half-Life 2 WILL set new standards for every game that precedes it to try to brake, what more can you ask for in a game?

Half-Life takes advantage of licensed technology from id Software, but adds a whole new level of proprietary technology. Just a few of the technological advancements include:
Renderer

• Version 2.0 (and below) shaders, bump mapping, LOD on models and world
• Author shaders with HLSL
• Cube and environment mapping
• Dynamic lights, vertex lighting and light maps, many light types including flickering, pulsing etc.
• High-Dynamic Range lighting
• Water with refraction and fresnel effects
• Advanced particle system that can emit sprites or models
• Projected shadows allow for a large number of characters per scene
• Occluder entities for visibility blocking
• Indoor/Outdoor environment
  • Deformable terrain
  • 3D skyboxes extend the horizon and add parallax on distant objects
  • Dynamically rendered organics (grass, trees etc)
• Subdivision surfaces, diffuse & specular bump maps
• Real-time radiosity lighting
• Effects include but are not limited to: particles, beams, volumetric smoke, sparks, blood, environmental effects like fog and rain
• Scalability
  • Dx6-Dx9 hardware supported

Materials System

• Instead of traditional textures, Source defines sets of materials that specify what the object is made from and the texture used for that object.  A material specifies how an object will fracture when broken, what it will sound like when broken or dragged across another surface, and what that object’s mass and buoyancy are.  This system is much more flexible than other texture only based systems.
• Materials can interact with objects or NPCs such as mud or ice for vehicles to slide/lose traction on.

Multiplayer Network Code

• Time and gamer tested by millions of gamers around the world
• Support for both LAN based multiplayer and Internet based multiplayer games
• Prediction analysis for interpolating collision/hit detection
• Optimizations for high-latency, high-packet loss 56k connections 

Advanced Characters

• Detailed and believable characters
• Realistic eyes
  • Focus on player/object, not simply parallel views
  • Proper eye “bulge” for realistic eye reflections
• Simulated musculature provides outstanding emotions, speech and body language
• Language independent speech, characters can naturally speak in many languages
• Skeletal/bone system for animation
• Layered animation system can synthesize complex animations out of several pieces

Physics

• More responsive world with realistic interactions
• Sounds & graphics follow from physics
• AI characters can interact with physically simulated objects
• Ropes/cables, machines, constraint systems, ragdoll physics
• Can be controlled by level design
• Kinematic animated bone followers
• Custom procedural physics controllers
• Vehicles
  • Wheels slip and skid
  • Realistic suspensions with springs on each wheel
  • Realistic leaning during acceleration/deceleration and turning
  • Individually tunable parameters such as horsepower, gearing, max speed, shift speed, tire material, tire friction, spring tension/dampening etc.
  • Multiple players in a vehicle in multiplayer
  • Hovercraft support for cheaper simulation

Advanced AI

• I/O system allowing level designers to control AI
• Sophisticated navigation: characters that run, fly, jump, crouch, climb stairs and ladders, and burrow underground
• AI senses things using sight, sound, smell
• AI relationships determine friend/foe status of other entities
• Battle AI allows squads of AI characters to operate together, know when to advance, retreat, lay cover fire, etc. 
Sound
• 5.1 surround sound, 4 speaker surround
• High-quality 3D spatialization
• Custom software DSP
• Automatic DSP based on environmental geometry
• ADPCM decompression
• 16-bit 44KHz, stereo wave data with all features
• MP3 decompression (requires Miles license)
• Support for audio streaming on any wave
• Real-time wave file stitching
• Pre-authored Doppler effect encoded waves
• Pre-authored distance variant encoded waves

UI

• Server browser - Displays all active game servers and allows a player to choose which one to participate on.  Players can filter and sort server lists in order to speed up the display and selection of a server.
• Friends instant messenger - Allows players to message each other both in and out of the game as well as join friends in existing games.  No more confusion about what server your friends are on, you can easily join with this feature.
• VGUI – Valve’s custom GUI interface mimics most of the windows controls but is rendered using the Source engine for both in game and out of game uniform UI display.  VGUI is platform independent and is Unicode compliant for ease of localization

Programming

• All code written in C/C++ using Visual Studio 6.0.  Easily and quickly derive new entities from existing base classes.
• Internal context sensitive performance monitoring system
• Graphics performance measurement tools built into the engine
• Modular code design (via DLL’s) allows swapping out of core components for easy upgrading or code replacement
• Dx9 shaders all written in HLSL

Tools

• Faceposer
  • Facial expression tool used to craft speech and emotions
• Valve Hammer Editor
  • WYSIWYG World editor
  • Create world brushes
  • Terrain editor
  • Place detailed world models and AI NPCs
  • Set navigation points/paths for NPCs
  • Place triggers, clip brushes, logic etc.
  • Allows level designer to hook up I/O between entities to control AI within the game|
• Half-Life Model Viewer
  • Full model previewer
  • Rotate models in any direction
  • Setup hit boxes
  • View physics hull
  • View normals
  • Wireframe, shaded or textured view modes
• Studiomdl
  • Model compiler
• Vbsp, Vrad, Vvis, VMPI
  • Map compilation tools (bsp, lighting and visibility)
  • VMPI – distributed compilation tool allowing level compiles to be spread across many pc’s greatly reducing compile times
• Exporters
  • XSI, Max and Maya .smd exporters for exporting 3D models

	Antlion Lives in the sand, and lurks around under Nova Prospekt. These Antlions attack swiftly, and always travel in packs. However, you can lure them to do your bidding with the scent of Pherapods.		Antlion Guard The bigger, more bad-ass version of the Antlion. You can't lure Antlion Guards with the Pherapods, so you're going to have to toss barrels and cap a bunch of shells in this big momma to take it down.
	Barnacle Just like the Barnacles from the original Half-Life, it'll pick up anything with it's excessively long and powerful toungue. However it doesn't know what it's picking up, so why not give it a flamable barrel to chew on?		Headcrab These annoying so-called 'headhumpers' return from the original game. These headcrabs have the same attributes as last time, but now they're a little bit more responsive, and they come in different types. Oh no!
	Fast Headcrab This is the first variation of the headcrab, but don't underestimate this one, because it is so goddamn fast it's going to bunnyhop into your face. Seriously.		Poison Headcrab Now it's the perfect time to crap your pants. For the first time ever, you can actually be scared by a headcrab...a poison one that is. Once the poison headcrab touch you, you will instantly lose all your health. But luckily, your HEV suit will inject antidote into you, and you will slowly regain all of your previous health.
	Zombie Just the the headcrab, it's back, and it comes in different forms. This zombie is a little bit smarter than the one in the last game, just make sure you're not too close to them because they will gang up on you, and toss barrels and tables at you.		Fast Zombies Now this type of zombie, is seriously dangerous, and scary. They will run to you at an unbelievable speed, and well...once it reaches you, it's over. Unless you pop a couple of shotgun shells in its head, then you can easily kill them.
	Poison Zombie This one isn't as scary as the fast zombies, however you shouldn't underestimate this one, nor walk up to it. You can either wait for the zombie to toss the poison headcrabs at you, or you can lob a grenade in front of it.		Ichthyosaur Actually, you won't encounter any Ichthyosaurs in Half-Life 2, unfortunately. The only times you will see them are in one of the cutscenes, and if you fall into the sea, and you'll get eaten.
	Leeches Same as the Ichthyosaur, you won't actually encounter any of these unlike the original game. You will only see them if you go too deep into the water, and you'll get your face eaten.

	G-Man The mysterious G-Man, also known as the Government Man, watches over Gordon throughout the Resonance Cascade. The G-Man was impressed by Gordon's survival of the incident, and he offered Gordon a job that he couldn't decline. Now, the G-Man brings Gordon to City 17 and assists him in his next 'mission'.		Alyx Vance She is the young and talented daughter of Eli Vance. Alyx finds you struggling in City 17, and becomes your ally to fight against the Combine.
	Eli Vance Eli was one one of your colleagues back in Black Mesa, he was also a survivor in the Resonance Cascade. However, his wife Azian didn't make it through the incident, he is Alyx's father and he's very protective of her.		Barney Calhoun He was your ass-kicking sidekick from Black Mesa, and he is still kicking some serious ass in City 17. You will meet up with Barney alot in the streets of City 17.
	Dr. Isaac Kleiner & Lamarr Dr. Kleiner was another of your scientist pals from Black Mesa. On his way out of the Black Mesa facility, he found a harmless headcrab which soon became his adorable 'pet', named Lamarr. Even though Kleiner says that Lamarr is completely harmless, she seems to have a grudge with Barney all the time.		Dr. Wallace Breen Breen was the administrator in Black Mesa. When the Resonance Cascade was triggered and the Combine Overwatch was taking over Earth, he cowardly surrendered to the Combine, betrayed humanity, and soon became the leader of the Combine Overwatch
	Dr. Judith Mossman Judith was the last of the survivors at Black Mesa. She was very jealous about how it should've been her in the test chamber in Black Mesa instead of Gordon. It seems that Judith and Alyx always has a very serious conflict with each other, and they never get along.		Father Gregori He is a genius...as well as a maniac. This holy man lurks around setting traps and killing the undead in the zombie-infested town of Ravenholm.
	Dog He is a lovable, tiny pet that Eli built to protect his daughter...until Alyx starting building and adding on to Dog. Now he is an unstoppable, over-sized monster that will greatly help you on your mission.		Citizen Rebels The resistance force of City 17 will eventually meet up with Gordon to assist him as much as they can, to fight against the Overwatch.

	Crowbar Firepower: Weak Ammo capacity: N/A Secondary function: None The crowbar makes a return from the original game, and it looks sexier than ever. The crowbar will be your weapon of choice when it comes to crackin' up supply crates, breaking wood, or just beating up some headcrabs.		9mm Pistol (USP Match) Firepower: Weak Ammo capacity: 18 per clip, 150 reserved Secondary function: None The good old Glock is replaced with the sleek-looking USP Match. It has a fairly large clip for a pistol, sporting eighteen 9mm bullets in a clip. Its fast firing rate makes up for its weak firepower.
	.357 Magnum Firepower: High Ammo capacity: 6 per clip, 12 reserved Secondary function: None It only holds 6 rounds, and it reloads pretty slowly, but it's amazing firepower and accuracy will make up for its flaws. This is the perfect weapon for quick sniping, or clearing out narrow hallways.		Sub-Machinegun (MP7) Firepower: Medium (primary), Very high (secondary) Ammo capacity: 45 per clip, 255 reserved, 3 grenades Secondary function: Launch impact grenade This new MP7 sub-machinegun is the replacement for the MP5 back in Black Mesa. It's got average firepower, the accuracy is pretty decent, and the reload time is pretty quick, so remember to strafe and shoot at the same time, and stop behind something to reload. The MP7 has a built-in grenade launcher, it will launch grenades that will explode on impact to a surface or enemy.
	Shotgun Firepower: High (primary), Very high (secondary) Ammo capacity: 6 loaded, 30 reserved Secondary function: Double-barrel shot You will find yourself using the shotgun alot in the game, especially in Ravenholm. A nice double-barrel shot to a fast zombie's head will take them out instantly. The shotgun is extremely powerful, so make sure you get up close to the enemy then pull the trigger!		Frag Grenade Firepower: Very high Ammo capacity: 1 equiped, 4 reserved Secondary function: Short-range roll Grenades are very effective and entertaining when you lob one in front of a group of enemies, watch them blow up and watch the ragdolls soar through the air. However, it ain't that pretty if they do that to you, this is why you quickly whip out your Gravity Gun, shoot it back at them, and watch them get a taste of their own medicine.
	Rocket Propelled Grenade Launcher Firepower: Very high Ammo capacity: 1 loaded, 2 reserved Secondary function: None The powerful RPG returns, and it's even more useful now! The RPG is perfect for clearing out a large number of Combine Soldiers when it gets kind of heavy, shooting down Gunships, and knocking down Striders!		Overwatch Standard Issue Pulse Rifle Firepower: High (primary), Very high (secondary) Ammo capacity: 30 per clip, 60 reserved, 3 orbs Secondary function: Launch energy orb The Pulse Rifle is basically a beefed up alternative to the sub-machinegun, though it lacks in ammo capacity. The secondary will launch a piercing energy orb, which will tear up most enemies in an instant. Launch one in a small room full of combine and watch the orb bounce off walls and pierce through soldiers, woot!
	Zero Point Energy Field Manipulator (Gravity Gun) Firepower: N/A Ammo capacity: None Secondary function: Grab object The Gravity Gun is a very unique weapon that puts physics to use. This gun can grab any light to medium weight item using secondary fire and move it around, but during combat, you can toss the object forward by using the primary fire while grabbing something. Flamable barrels and razor blades are great to grab and toss during combat, and you can grab unreachable supply crates too.		Pherapod Firepower: N/A Ammo capacity: N/A Secondary function: Recall Antlions The Pherapod is indeed another unique weapon. With these smelly balls, you can fool Antlions to do your bidding and fight for you, however you can only use the Pherapod for a small portion of the game. Secondary fire will make you squeeze the ball to emit more scent, and the Antlions will follow you, recalling them.
	Crossbow Firepower: Very high Ammo capacity: 1 loaded, 5 reserved Secondary function: Scope zoom The last of the classic weapons, but definately not least. The Crossbow is Half-Life 2's sniper rifle. It's equiped with a burning hot bolt, so you know it's powerful. Use the secondary fire to zoom in the scope, pull the trigger and watch the burning stick pierce through the Combine Soldier and stick to the wall. Awesome!