Half-Life 2, the sequel to Half-Life, is a first-person shooter video game and a signature title in the Half-Life series. Developed by Valve Corporation, it was initially released on November 16, 2004, following a protracted five-year, $40 million development cycle, during which a substantial part of the project was leaked and distributed on the Internet.
The game was developed alongside Valve's Steam software. It introduced the Source game engine and, because of Steam, is the first video game to require online product activation.
Like its predecessor, Half-Life 2 was met with near-unanimous critical acclaim. It was praised for its advanced physics, animation, sound, AI, graphics, and narrative. The game won 39 "Game of the Year" awards, and a couple of publications have named it "Game of the Decade". Over 6.5 million copies of Half-Life 2 were sold at retail by December 3, 2008, making it a bestselling PC game (not including the number of sales via Steam). As of February 9, 2011, Half-Life 2 has sold over 12 million copies.
Half-Life 2, like its predecessor Half-Life, is a singleplayer first-person shooter broken into chapters, permanently casting the player as Gordon Freeman. The sequel has nearly the same mechanics as Half-Life, including health-and-weapon systems and periodic puzzles. The player also starts without items, slowly building up an arsenal over the course of the game. Despite the game's mainly linear nature, much effort was put into making exploration rewarding and interesting; many optional areas can be missed or avoided.
A diverse set of enemies are present, which usually require being approached with different tactics: some coordinate in groups to out-maneuver or out-position the player, others, like the Manhack, fly directly at the player through small openings and tight corridors, some use predictable but powerful attacks, while others still are unarmed utilizing melee and/or swift movement, relying on lurking and/or obfuscation. Gordon can kill most enemies with his weapons, or make use of indirect means, exploiting environmental hazards such as explosive pressurized canisters, gas fires or purpose-built trap-mechanisms. At one point in the game, Gordon can be joined by up to four armed Resistance soldiers, and can send his team further from him or call them back; however, most are either in their general attire or have appropriated the flak vests that the civil protection wear, and as a result they can still die easily. Squad members are indicated on the HUD (squad member icons with a cross sign are field medics).
Many of the game's new features utilize its detailed physics simulation. Two sections of the game involve driving vehicles. Instead of button-based puzzles from Half-Life, environmental puzzles are also introduced with makeshift mechanical systems, revolving around the player's new ability to pick up, move, and place objects. Solutions involve objects' physical properties, such as shape, weight, and buoyancy. For example, in Chapter 3, Route Kanal, the player is required to stack cinder blocks on a makeshift see-saw ramp to proceed.
Part-way through the game, Gordon acquires the Gravity Gun, which allows him to draw distant objects towards himself or forcefully push them away, as well as to manipulate larger and heavier objects than he is able to alone. These abilities are required to solve puzzles later in the game, and can also be used to great effect in combat, since any non-static object within proximity to the player has the potential to be used as a makeshift defense or a deadly projectile.
The game does not contain pre-rendered or scripted cutscenes; the story proceeds via exposition from other characters, as well as events that unfold in the game world and never leaves Gordon's perspective.