First-person shooter where you play Gordon Freeman fighting through an occupied Earth roughly two decades after the Black Mesa incident. The Combine, an interdimensional empire, has turned City 17 into a surveillance state. You'll navigate canals in an airboat, drive a buggy down coastal highways, and storm a prison fortress. The Gravity Gun lets you weaponize physics—hurl saw blades, punt explosive barrels, stack crates as cover. Friendly AI characters like Alyx Vance accompany you through stretches of the campaign, reacting to combat and commenting on the environment. Enemies flank, take cover, and radio for backup. Ravenholm's zombie-infested ruins and the Citadel's sterile tech corridors show the range. Environmental puzzles use physics: balance seesaws with debris, jam gates with metal beams. It's linear but varied, swapping tools and tactics every few chapters.
