Development lasted five years and cost US$40 million. The game was created using Valve's Source engine, which was developed at the same time. Set roughly twenty years after the events of the first game, players control Gordon Freeman as he joins a resistance movement to liberate the Earth from the control of an alien empire called the Combine. Like the original Half-Life (1998), it combines shooting, puzzles, and storytelling, and adds features such as vehicles and physics-based gameplay. Half-Life 2 is a 2004 first-person shooter game developed and published by Valve.
