Half-Life 2 superior to the original in graphics and physics. In the sequel, the gameplay became more varied. There were episodes involving trips by transport. The locations have become more diverse due to the fact that the action now takes place not in a scientific complex, but in a metropolis and its environs in Eastern Europe.

In Half-Life 2, the arsenal of weapons has increased and partially changed. In close combat, the classic protagonist uses a crowbar. For attacks at a distance there is a pistol and a revolver, a shotgun, a submachine gun, a crossbow, a pulse rifle, and a rocket launcher. The barrels have an alternative firing mode. For example: on a machine gun, an under-barrel grenade launcher is activated, and the gun fires a double shot. The hero can also fire from stationary guns, lay mines and throw grenades. A gravity gun appeared. She can attract and repel objects. This gadget can be used to solve puzzles and used as a weapon, throwing circular saw blades, explosive barrels and other objects at enemies.

The variety of opponents has also increased. Alliance patrol soldiers, antlions, striders, manhacks, and stormtroopers were added. Headcrabs and zombies are here to stay. The campaign consists of 13 levels. Its action takes place a couple of decades after the end of the events of the first part. G-Man brought Gordon Freeman out of stasis and transferred him to City 17. There, the hero learns that during his absence the Seven Hour War happened. The inhabitants of the world of Zen began to enter Earth through portals in large numbers. And because of this, other aliens paid attention to the planet and captured it in the shortest possible time. A new government was formed led by Wallace Breen, the former administrator of Black Mesa, who persuaded humanity to surrender. The aggressors established a dictatorship, prohibited people from reproducing and began conducting experiments on them. The Resistance contacts the hero. In the ranks of the rebels, he meets familiar characters from the original game.