Excellent Game of Half-Life series
Since Half-Life 2 is a first-person shooter, the gameworld is always presented from Gordon Freeman's perspective. A heads-up display at the bottom of the screen shows the player's health, energy, and ammunition status, while a toggle screen shows available weapons at the top. Health and energy can be replenished by picking up medical supplies and energy cells respectively, or by using wall-mounted charging devices.
The player defeats enemies with an assortment of weapons. The game's available arsenal consists of modern-day projectile weapons, including a ubiquitous pistol, shotgun, and submachine gun, though more elaborate, fictional weapons are available, such as a crossbow that shoots hot metal rods, a pheromone pod that guides certain previously hostile alien creatures, once acquired, and pulse rifle that shoots glowing pulses and a secondary "Dark energy ball," which disintegrates enemies on contact. The Source engine's physics capabilities extend into combat via a special device called the Zero-Point Energy Field Manipulator, or "gravity gun." Using this device, the player can pick up objects and either hurl them at enemies or hold them in place to create a makeshift shield. The gravity gun can also perform a variety of non-combat functions, such as grabbing out-of-reach supplies, forming bridges across gaps, and flipping overturned vehicles.
Many puzzles use the game's physics engine. For example, one puzzle requires the player to either turn a seesaw-like lever into a ramp by placing cinder blocks at one end, or to stack wooden crates to form a crude stairway. Puzzles are frequently solved with the gravity gun. One puzzle has the player clear a highway by using the gravity gun to push numerous abandoned vehicles out of the way.
Another major development from the original Half-Life is the introduction of vehicular sections; while the original featured several sections on trains, the sequel features sections where the player makes use of fully functional vehicles such as cars or boats.