A Classic and a Masterpiece
I personally like to classify Half-Life as the best game ever created, but that's just my opinion. However, Half-Life did change the face of gaming with the first successful use of squad tactics and AI, complete lack of cut scenes, One of the greatest and most confusing plotlines ever, and a completely silent protagonist (Gordon Freeman).
The player takes control of Gordon right from the get go. The game begins on a tram ride that is on it's way into the Black Mesa Research Facility in New Mexico. Once Gordon arrives, he must don his HEV Mark IV hazard suit to prepare for a special experiment that, of course, goes horribly wrong and only gets worse. This is the beginning of the real game. The player must claw their way through the carnage and destruction that is now Black Mesa back to the surface to call for help.
This game is a must have because it constantly delivers and still offers an amazing, memorable experience for today's gamers. If you don't have this game (weirdo) and are a fan of first person shooters, do yourself a favor and get Half-Life... Now.