It was delayed by over a year, triggering a backlash. Valve announced Half-Life 2 at E3 2003, with a release date for that September. They integrated Havok physics into the game engine, which simulates real-world physics, to reinforce the player's sense of presence and create new gameplay, and developed the characterization, with more detailed character models and realistic animation. Valve's president, Gabe Newell, set his team the goal of redefining the FPS genre. Development lasted five years and cost $40 million.
Half-Life 2 was created using Valve's Source engine, which was developed at the same time. Players control Gordon Freeman as he joins a resistance movement to liberate the Earth from the control of a multidimensional alien empire, the Combine. Like the original Half-Life (1998), Half-Life 2 combines shooting, puzzles, and storytelling, and adds features such as vehicles and physics-based gameplay. It was first published by Valve for Windows through its distribution service Steam. Half-Life 2 is a 2004 first-person shooter (FPS) game developed by Valve.
