Gordon Freeman! The scientist turned alien killer... and zombie slaughterer... and... improbable hero?! Heck yeah.
Also something important to note are the weapons. They are cool and feel at times realistic. Your bullets will not go on a straight line, recoil and movement will make your weapons more inaccurate, except for a few weapons that have 100% accuracy, such as the crossbow, that nails the combine into the walls, and the magnum revolver, that packs a lot of punch for such a small gun. Other weapons include machine guns and shotguns. Some of the guns even feature secondary shooting modes, such as firing two rounds at the same time with a shotgun, firing explosives or cool energy balls that disintegrate the enemy. Nevertheless, one weapon and tool that stands apart from all other weapons is the Gravity Gun. With this gun, you can move heavy object by levitating them, and you can also throw them very large distances, making all heavy objects lethal weapons when tossed at enemies. Towards the end of the game, the gravity gun gets an upgrade and you can even pull and toss enemies and kill them instantly.
The source engine really shows off with this game. Physics are very cool, demanding to solve many puzzles, such as piling boxes to reach high areas, or by watching an explosion sending away the combines into air and shattering wood to small pieces. The game is a technical beauty. Animation is fluent and attractive. Sound is clear and impressive.
Half Life 2 is a game worth checking. It is not like any other FPS, and even though you have to move from point A to point B, the amount of detail poured into the game and a sense of freedom infused by the very levels themselves gives this game a life that distinguish it form other shooters. There is a lot of variety, such as boat an car sequences, but some firefights are truly memorable. You are in the middle of a battle for earth, and you are leading it. Horror also is included inside the game with many kind of zombies and crab heads that come after you in dark areas, where the use of flashlight reveals creepy environments like the dead Ravenholm, that are in contrast with technological juggernauts such as The Citadel. The dialogues that happen in real time and the facial expressions that where achieved by the animation of every character are remarkable and enjoyable, which add a lot to the immersion to the game.
In conclusion, you should play Half Life 2, at least give it a try. It is a great game that has been polished from start to finish for the best experience possible... that is until they released Episode 1! And later, Episode 2. But that's another story.